Proposed Regulations for Revisions to the Federal Test Procedure for Emissions From Motor Vehicles

SUMMARY: This notice proposes additions and revisions to the tailpipe

emission portions of the Federal Test Procedure (FTP) for light-duty

vehicles (LDVs) and light-duty trucks (LDTs). The primary new element

of the proposal is a Supplemental Federal Test Procedure (SFTP)

designed to address shortcomings with the current FTP in the

representation of aggressive (high speed and/or high acceleration)

driving behavior, rapid speed fluctuations, driving behavior following

startup, air conditioning, and intermediate-duration periods where the

engine is turned off. An element of the SFTP that also affects the

conventional FTP is a new set of requirements designed to more

accurately reflect real road forces on the test dynamometer. The Agency

is also proposing new emission standards for the new control areas with

a specified phase-in period for these standards. After complete fleet

turnovers, the standards proposed today are estimated to reduce

emissions from LDVs and LDTs by eight percent for non-methane

hydrocarbons (NMHC), 18 percent for carbon monoxide (CO), and 14

percent for oxides of nitrogen (NOX).

DATES: Written comments on this NPRM must be submitted on or before 30

days after the public hearing date. The Agency will conduct a public

hearing on this NPRM approximately March 24, 1995. The date of the

public hearing will be published in a future Federal Register document.

ADDRESSES: Interested parties may submit written comments (in duplicate

if possible) to Public Docket No. A-92-64, at: Air Docket Section, U.S.

Environmental Protection Agency, 401 M Street SW, Washington, DC 20460.

The public hearing will be held at a location to be published in a

future Federal Register document.

Materials relevant to this proposed rulemaking have been placed in

Docket No. A-92-64. The docket is located at the above address in Room

M-1500, Waterside Mall, and may be inspected weekdays between 8:30 a.m.

and 5:30 p.m. A reasonable fee may be charged by EPA for copying docket

materials.

FOR FURTHER INFORMATION CONTACT: John German, Certification Division,

U.S. Environmental Protection Agency, National Vehicle and Fuel

Emissions Laboratory, 2565 Plymouth Road, Ann Arbor, Michigan, 48105.

Telephone (313) 668-4214.

SUPPLEMENTARY INFORMATION:

Table of Contents

I. Obtaining Copies of the Regulatory Language

II. Introduction

III. Proposal Requirements and Alternative Approaches

IV. Statutory Authority and Legal Analysis

V. The FTP Review Project and Areas of EPA Concern

VI. In-Use Behavior

VII. Representative Driving Cycles

VIII. Emission Inventory Assessments

IX. Cause and Control of Emissions

X. Other Options and Information Needed

XI. Environmental and Economic Impacts

XII. Public Participation

XIII. Administrative Designation

XIV. Regulatory Flexibility Act

XV. Reporting and Recordkeeping Requirement

I. Obtaining Copies of the Regulatory Language

Electronic copies (on 3.5'' diskettes) of both the proposed

regulatory language and the Support Document to the Proposed

Regulations for Revisions to the Federal Test Procedure: Detailed

Discussion and Analysis, Regulatory Impact Analysis (RIA), and

Technical Reports may be obtained free of charge by visiting, calling,

or writing the Environmental Protection Agency, Certification Division,

2565 Plymouth Road, Ann Arbor, MI 48105, (313) 668-4384. Refer to

Docket A-92-64. A copy is available for inspection in the docket (See

ADDRESSES).

The proposed regulatory language and the Support Document to the

Proposed Regulations for Revisions to the Federal Test Procedure:

Detailed Discussion and Analysis, RIA, and Technical Reports are also

available electronically on the Technology Transfer Network (TTN). TTN

is an electronic bulletin board system (BBS) operated by EPA's Office

of Air Quality Planning and Standards. Users are able to access and

download TTN files on their first call. The steps required to access

information on this rulemaking are listed below. The service is free,

except for the cost of the phone call.

TTN BBS: 919-541-5742 (1,200-14,400 bps, no parity, eight data bits,

one stop bit)

Voice help: 919-541-5384

Internet address: TELNET ttnbbs.rtpnc.epa.gov Off-line: Mondays from

8:00-12:00 Noon ET

1. Technology Transfer Network Top Menu: GATEWAY TO TTN TECHNICAL

AREAS (Bulletin Boards) (Command: T)

2. TTN TECHNICAL INFORMATION AREAS: OMS--Mobile Sources Information

(Command: M)

3. OMS BBS === MAIN MENU FILE TRANSFERS: Rulemaking & Reporting

(Command: K)

4. RULEMAKING PACKAGES: [Light-Duty] (Command: 1)

5. Light-duty Rulemaking Area: File area #1 ... FTP Review (Command: 1)

At this stage, the system will list all available FTP Review files.

To download a file, select a transfer protocol which will match the

terminal software on your computer, then set your own software to

receive the file using that same protocol.

If unfamiliar with handling compressed (that is, ZIP'd) files, go

to the TTN top menu, System Utilities (Command: 1) for information and

the necessary program to download in order to unZIP the files of

interest after downloading to your computer. After getting the files

you want onto your computer, you can quit TTN BBS with the oodbye

command.

II. Introduction

Automobiles are among the largest producers of hydrocarbons (HC),

carbon monoxide (CO), and oxides of nitrogen (NOX), all of which

have documented impacts on public health. Hydrocarbons and oxides of

nitrogen contribute to the formation of ozone, a powerful oxidant which

irritates the respiratory system and reduces lung function. Some

studies indicate that ozone may permanently damage lung and other

tissues. Elevated levels of CO decrease the ability of blood to

transport oxygen throughout the body, which tends to exacerbate

cardiovascular stress. High ambient levels of CO can also adversely

affect the central nervous system, and the presence of CO in even

moderate levels in the bloodstream may impact the health of fetuses and

newborns.\1\ After complete turnover of the fleet, the Agency believes

that the changes proposed today would result in an eight percent

reduction in non-methane hydrocarbons (NMHC), an 18 percent reduction

in CO, and a 14 percent reduction in NOX emissions from

[[Page 7405]] automobiles during typical summertime ozone exceedance

days.

\1\Regulatory Impact Analysis for FTP Revisions, U.S. EPA,

Office of Air and Radiation. Available in the public docket for

review.

---------------------------------------------------------------------------

The Agency has established a number of emission standards for motor

vehicles and engines, designed to control air pollution by reducing in-

use emissions from motor vehicles. Compliance with these standards is

typically measured using a test procedure that simulates in-use

driving. In 1990, Congress amended the Clean Air Act with passage of

the Clean Air Act Amendments (hereafter, CAAA or Amendments) and

required that EPA review these test procedures and revise them as

appropriate to reflect in-use conditions. The Agency's review focused

on the procedures for light-duty motor vehicles, especially the Federal

Test Procedure (FTP), the procedure used to measure compliance with

motor vehicle tailpipe and evaporative emission standards.

The Agency, in conjunction with automobile manufacturers and

California's Air Resources Board (CARB), conducted an extensive review

of in-use driving behavior, obtaining a wealth of data on how cars are

driven during trips, the length of trips, the length of time between

trips, and so on.2 The Agency then generated representative

driving cycles from the data and conducted emission testing to compare

emissions over these cycles with emissions over driving cycles used in

the FTP. These results confirmed that revisions to the FTP were needed,

as significant emissions were seen under conditions not represented by

the current FTP.

\2\See the ``Federal Test Procedure Review Project: Preliminary

Technical Report,'' EPA 420-R-93-007 and the Technical Reports for

this rulemaking, both in the public docket, for descriptions of the

surveys and data gathered.

---------------------------------------------------------------------------

The Agency sought an approach which would extend the level of

control found under current FTP conditions across all in-use driving

behavior. Thus, EPA developed various changes to the FTP, focusing on

new driving cycles to add to the current FTP. The Agency also

investigated possible control technologies that could be used to

control emissions over these new compliance cycles. Today's proposal

includes these various changes in the test procedure for tailpipe

emissions, as well as the emission standards related to them.

In developing new compliance cycles, EPA did not re-evaluate the

stringency of current standards. Rather, EPA sought parity between the

types and extent of controls that manufacturers currently employ to

comply with existing FTP standards and those they would implement to

comply across all driving behavior. Thus, EPA believes that

manufacturers for the most part will comply by making simple changes to

their existing calibration strategies.

BILLING CODE 6560-50-P

[[Page 7406]]

[GRAPHIC][TIFF OMITTED]TP07FE95.000

BILLING CODE 6560-50-C

[[Page 7407]]

The FTP is the core procedure used to measure compliance with

emission standards for light-duty vehicles (LDVs) and light-duty trucks

(LDTs). The current version of the FTP (40 CFR 86.130-96) consists of a

series of preparatory steps to ensure the vehicle has been properly

preconditioned on the test fuel, periods when the engine is off between

vehicle operation (called ``soaks''), and emission tests which measure

tailpipe and evaporative emissions. Tailpipe emissions are measured

while the vehicle is operated according to a specified driving cycle on

a dynamometer. Figure 1 presents the Urban Dynamometer Driving

Schedule, commonly referred to as the LA4. With the exception of

running losses, which are measured during dynamometer operation,

evaporative emissions are measured in a sealed enclosure while the

vehicle is turned off. An additional cold temperature CO test procedure

measures tailpipe emissions at 20 deg. F following a cold soak. By

comparing the emission test results to emission standards applicable to

a given vehicle class, combustion cycle, and motor fuel, EPA determines

if the vehicle meets applicable certification or in-use

requirements.3

\3\The Agency has historically relied on emission performance

standards because they directly limit production of exhaust

constituents that affect attainment of the National Ambient Air

Quality Standards, while providing maximum flexibility to the

vehicle manufacturers in determining cost-effective compliance

strategies. Other basic compliance program approaches include system

performance standards, which set bounds on measurable performance

parameters of the engine or emission control system rather than

actual emission levels, and design standards, which prescribe

primary design elements of the engine or control system.

---------------------------------------------------------------------------

The current evaporative emission procedure, including refueling,

and cold temperature CO test procedures were promulgated following

passage of the Amendments. Thus, the test procedures in these rules

were recently developed to reflect the actual current driving

conditions under which motor vehicles are used (57 FR 31888; 58 FR

16002). The Agency is not proposing to change these test procedures and

the remainder of this section and the subsequent proposal focuses on

the light-duty tailpipe emission testing procedures of the FTP.

The FTP simulates on-road vehicle operation using a dynamometer in

a laboratory test cell held between 68 deg. F and 86 deg. F. The

vehicle is driven on the dynamometer over cycles that prescribe the

vehicle operator's speed as a function of time. The method for

measuring tailpipe emissions of HC, CO, and NOx requires filling a

bag with exhaust drawn from the tailpipe and diluted with background

air while the vehicle is driven over the appropriate cycle. The bagged

sample is analyzed for the concentrations of exhaust constituents,

which serve as inputs to subsequent emission compliance calculations.

Additional procedures apply to the sampling of particulate matter from

diesel-cycle vehicles and organic gases from alternative-fuel vehicles.

III. Proposal Requirements and Alternative Approaches

Today's proposal deals primarily with five areas of driving

behavior that have not previously been represented in the test

procedure: aggressive driving behavior (such as high acceleration rates

and high speeds); rapid speed fluctuations (microtransient driving

behavior); start driving behavior; intermediate soak times (engine-off

times between 10 minutes and 2 hours prior to vehicle start); and

actual air conditioner (A/C) operation. The Agency is proposing new

requirements for these areas, separate from the existing FTP

requirements. Also included in this proposal are requirements to

improve the simulation of actual road load forces4 across all

speed ranges and to revise the criteria for allowable speed variation

for a valid test, which would be applicable both to the new provisions

proposed in this NPRM and the existing FTP.

\4\Road load forces refers to the force needed to overcome wind

and tire resistance when driving at specific speeds.

---------------------------------------------------------------------------

As most of this proposal deals with areas that have not previously

been regulated, the Agency is considering a broad range of alternative

approaches and requests. Comment on the alternative approaches, as well

as the central proposal, are requested. Depending on comments and data

received and analyses conducted subsequent to today's proposals, EPA

may include some of the alternatives, in whole or in part, in the final

rule. Interested parties may also submit comments on alternatives not

specifically identified or analyzed by EPA for this proposal.

While both the central proposal and the alternatives are EPA's own

design, they incorporate some concepts put forth both by the California

Air Resources Board (CARB) and the Ad Hoc Panel on Revisions to the FTP

(Ad Hoc Panel), a joint committee of the American Automobile

Manufacturers Association (AAMA) and the Association of International

Automobile Manufacturers (AIAM).

The proposed additions and revisions to the tailpipe emission

portions of the FTP would apply to all LDVs and LDTs, certifying on all

current motor fuels. The proposed changes would apply to testing

conducted during certification, Selective Enforcement Audits, and in-

use enforcement (recall). Adjustments are included to accommodate

certain vehicle types, transmission types, and performance categories

where the additions are not representative of in-use driving. The

Agency solicits comments and data on the appropriate treatment of

vehicles for which adjustments are allowed and the methods for making

the adjustments.

A. Central Proposal

The central proposal relies on a new Supplemental Federal Test

Procedure (SFTP) that addresses various conditions under which vehicles

are actually driven and used, which are not in the FTP. The SFTP

includes three new driving cycles to represent (1) aggressive driving

(as characterized by high speeds and/or high accelerations); (2)

driving immediately following vehicle startup; and (3) microtransient

driving (rapid speed fluctuations), which occur across the majority of

the normal ranges of operating speeds and accelerations. The proposed

SFTP incorporates conditions that are designed to more accurately

reflect actual engine load due to A/C operation under typical ozone

exceedance conditions. A new intermediate-duration (10- to 60-minute)

soak period is also included.

Two components of today's proposal have wider impacts than just the

SFTP. The first is to more accurately simulate real on-road loads at

the tire/dynamometer interface, which is an element of the proposal

that affects dynamometer operation throughout both the FTP and SFTP.

The second would remove language specifying ``minimal throttle

movement'' when conducting emission tests and replace it with

``appropriate throttle movement'' and require a specification of

allowable speed variation, which also impacts both SFTP and FTP

testing. The Agency is also requesting comment on whether the increased

sophistication of vehicle computers necessitates replacing existing

defeat device language with a requirement for proportional emission

control under conditions not directly represented by the FTP and the

SFTP.

The proposed standards would apply for full useful life under

section 202 of the Clean Air Act. The warranty provisions under section

207 of the Clean Air Act also apply to this rulemaking. [[Page 7408]]

Supplementary Federal Test Procedure--The SFTP includes three

single-bag emission test cycles: a hot stabilized 866 Cycle5 run

with a new simulation of in-use A/C operation; a new Start Control

Cycle (SC01, see figure 2) simulating driving with the new simulation

of in-use A/C operation and proceeded by a soak period; and a new

Aggressive Driving Cycle (US06, see figure 3) run in the hot stabilized

condition. The cycles of the SFTP can be run as a sequence to save on

preconditioning and setup time; however, separate runs of the cycles

are permissible with the appropriate soak or preconditioning steps

appended.

\5\5 Refers to Bag 2 of the LA4, preceding the 10-minute hot

soak, lasting 866 seconds.

---------------------------------------------------------------------------

BILLING CODE 6560-50-P

[[Page 7409]]

[GRAPHIC][TIFF OMITTED]TP07FE95.001

[[Page 7410]]

[GRAPHIC][TIFF OMITTED]TP07FE95.002

BILLING CODE 6560-50-C

[[Page 7411]]

Elements of the proposed A/C simulation for certification testing

include, a 95 deg.F 5 deg.F test cell ambient temperature,

A/C set to ``maximum A/C'' with interior air recirculation, high

interior fan setting, coldest setting on the temperature slide,

driver's window down, and front-end supplemental fan cooling. Although

certification testing would occur at 95 deg., the compliance

requirement would apply at less demanding temperatures as well. Thus,

EPA confirmatory testing could take place at any point across the range

68 deg.F to 95 deg.F. The compliance requirement would would The Agency

proposes these conditions as a cost-effective surrogate for testing in

a fully controlled environmental chamber set to simulate ozone-

exceedance conditions of ambient temperature, humidity, solar load, and

pavement temperature, although the use of a fully controlled

environmental chamber would be permitted.

The required elements for the SC01 include the preconditioning,

soak period, and compliance cycle requirements. Prior to the soak

period, the vehicle is to be preconditioned to allow engine and

catalyst temperatures to stabilize at typical warmed-up operating

temperatures. The Agency believes that running the vehicle over EPA's

Urban Dynamometer Driving Schedule (LA4) is adequate to achieve engine

and catalyst stabilization regardless of the time period for which the

vehicle was not operational prior to preconditioning. However, in the

event the vehicle was shut off for less than two hours prior to

preconditioning, the Agency believes that a 505 cycle is adequate for

preconditioning the vehicle, although the 866 or the SC01 is also

acceptable.

Immediately following the preconditioning cycle, the vehicle will

enter the soak period. Manufacturer testing of engine families required

to comply with the intermediate soak requirements for certification or

SEA testing must soak the vehicle for at least 60 minutes. EPA will

have the option of testing any soak duration between 10 and 60 minutes

for certification, SEA, and in-use testing. If the engine family is not

required to meet the intermediate soak requirements, a 10-minute soak

period is proposed. During this period, cooling fans directed at the

vehicle are to be shut off. The vehicle may be removed from the

dynamometer, provided the vehicle is not subjected to unrepresentative

cooling of the engine or catalyst. Following the soak period, the

vehicle will be run over the SC01 cycle using the proposed A/C

simulation for proper representation of engine and catalyst warm-up and

start driving.

The US06 driving cycle is designed to be run in hot stabilized

condition. High-volume exhaust flow for larger-displacement vehicles

run on US06 dictates use of a larger-capacity constant volume sampler

(CVS) than is needed for current FTP testing. The proposed A/C

simulation is not required for this test cycle.

The Agency proposes that manufacturers determine the appropriate

shift points for their manual transmission applications and submit the

shift schedules for EPA approval. In general, EPA will allow

manufacturers to specify upshift points, but downshifting will not be

permitted unless the vehicle is unable to stay within the driving

tolerance on the speed trace in the existing gear.

Hot stabilized condition is achieved by including several

preconditioning options as part of the formal procedure immediately

prior to the US06 Cycle. If the vehicle has undergone a soak of 2 hours

or less, the preconditioning may be a 505 Cycle, the 866 Cycle, US06,

or the SC01. Following longer soaks, the proposed preconditioning cycle

is an LA4. For manufacturers who have concerns about fuel effects on

adaptive memory systems, the proposal allows manufacturers, and upon

manufacturer request, requires EPA to run the vehicle over the US06

Cycle on the certification test fuel before entering the formal test

procedure.

The Agency proposes adjustments to the aggressive driving test

cycle for all heavy light-duty trucks (HLDTs),6 and also, for some

low- and high-performance LDVs and LDTs. The proposal calls for US06

Cycle testing of HLDTs with the truck ballasted to curb weight plus 300

lbs and the dynamometer inertia weight determined from this same basis,

while FTP testing remains at Adjusted Loaded Vehicle Weight. The

proposed US06 Cycle adjustments based on performance level are

summarized in Table 1. For low performance vehicles, the inertia weight

is adjusted by multiplying the original inertia weight by the

adjustment factor which is equal to the ratio of the applicable

performance cutoff and the W/P of the test vehicle. Where an adjustment

factor is called for, it is applied dynamically by the dynamometer only

during those portions of the US06 Cycle that are the most

aggressive.7 No adjustment factors are proposed for mid-

performance (``normal'') vehicles. For high performance vehicles, the

manufacturer must demonstrate stoichiometric control for wide-open

throttle events of two seconds or less in order to ensure that these

vehicles have aggressive driving emission control over similar vehicle

operation as the rest of the fleet.

\6\Light-duty trucks are divided into two weight categories

known as light light-duty trucks (rated up through 6000-pounds Gross

Vehicle Weight Rating (GVWR)) and heavy light-duty trucks (rated

greater than 6000-pounds GVWR).

\7\Refer to the Final Technical Report on Aggressive Driving

Behavior for the Revised Federal Test Procedure Notice of Proposed

Rulemaking for a detailed discussion of the points in the cycle

where the proposed adjustments would be made.

Table 1.--Performance-Based Adjustments

------------------------------------------------------------------------

Transmission Performance

type (W/P range) Adjustment

------------------------------------------------------------------------

manual......... low dynamic dynamometer inertia weight

W/P>34 reduction.

normal none.

18 W/P 34

high W/P31 reduction.

normal none.

18 W/P 31

high 2 second stoich control.

(W/PX, an

adjustment factor of 1.15 is applied to that standard to account for

the emission response of vehicles to the new A/C test conditions. See

the [[Page 7412]] Support Document to the Proposed Regulations for

Revisions to the Federal Test Procedure: Detailed Discussion and

Analysis for the specific numerical standards. Due to the absence of

relevant test data on which to base a decision, no supplemental test

procedures or standards are proposed for diesel particulate.

Included in the composite calculation are a cold start bag (based

on Bag 1 of the conventional FTP) and the three bags of the SFTP

(called Bag 4, 5, and 6). The weighting factor for each of the four

bags is adjusted as appropriate to reflect the proposed level of

control for each type of driving in the SFTP. Because the exhaust

constituents respond differently to the loads and speeds of the new

SFTP cycles, the proposed levels of control and, thus, the weighting

factors of the composite calculation differ somewhat for different

pollutants. The proposed weighting factors are:

------------------------------------------------------------------------

Percentages

-------------------------

THC/NMHC CO & NOX

------------------------------------------------------------------------

Bag 1 (cold start from FTP)................... 21 15

Bag 4 (866 cycle from SFTP)................... 24 37

Bag 5 (SC01 from SFTP)........................ 27 20

Bag 6 (US06 from SFTP)........................ 28 28

------------------------------------------------------------------------

The Agency is proposing that changes in the achievable levels of

control over the SFTP tests would track changes in the underlying FTP

standards and, thus, adoption of the central proposal would have the

effect of automatically reducing the composite standards in step with

any mandatory future declines in the FTP standards.8

\8\The issue of what standards would apply in the context of a

voluntary Federal low emission vehicle program will be determined in

a separate rulemaking (60 FR 4712, January 24, 1995).

---------------------------------------------------------------------------

Flexibilities are proposed to allow manufacturers to reduce their

testing burden, particularly during development testing. (See Support

Document to the Proposed Regulations for Revisions to the Federal Test

Procedure: Detailed Discussion and Analysis and Technical Reports for

discussion.)9

\9\Both the Support Document to the Proposed Regulations for

Revisions to the Federal Test Procedure: Detailed Discussion and

Analysis and the Technical Reports are in the public docket for

review.

---------------------------------------------------------------------------

Emissions Standards and Phase-in--The Agency is proposing to phase

in the proposed requirements for aggressive driving and air

conditioning control prior to implementing the intermediate soak

requirements. It is proposed that the standards apply to 40 percent of

each manufacturer's combined production of LDVs and LDTs for the 1998

model year, 80 percent in 1999, and 100 percent in 2000. Small volume

manufacturers would not have to comply until the 2000 model year. All

the proposed requirements would apply during this phase-in period,

except that Bag 5 could be conducted with a 10-minute soak instead of

the proposed 60-minute soak for control of intermediate soak emissions.

The 60-minute soak would be required for all vehicles starting with

model year 2001, including small volume manufacturers.

The Agency is continuing to analyze the impact of this phase-in

schedule, particularly when considered in conjunction with other

recently promulgated rules (such as revisions to the evaporative test

procedures) as well as potential future programs (such as voluntary

Federal low emission vehicle standards). Comments are specifically

requested (1) on the impact of this phase-in schedule when considered

with other programs and (2) providing suggestions for other schedules

which will coordinate programs more effectively. The Agency will review

this information in developing the final rule to determine if a more

logical coordination schedule is possible while maximizing the cost/

benefit effectiveness of this rule.

The proposal recognizes that adoption of emission standards more

stringent than current Federal Tier 1 standards will likely result in

emission control strategies that reduce catalyst light-off

times.10 This could have a significant impact on the costs and

benefits of the intermediate soak requirement. As Tier 1 standards are

the current legal requirement and the status of future standard changes

is uncertain at this time, this proposal presumes Tier 1 applicability.

The Agency invites comments and data addressing the cost/benefit

implications of the proposed soak requirement under a Federal Tier 2

(or equivalent) program.

\10\Time required for the catalyst to reach the temperature

needed to sustain significant catalytic activity.

---------------------------------------------------------------------------

Each of the test cycles is run on a system providing accurate

replication of real road load forces at the interface between drive

tires and the dynamometer over the full speed range. In addition, the

new US06 cycle requires significantly higher power absorption capacity,

due to the higher power requirements of this aggressive driving cycle.

While EPA intends to use a large-diameter single-roll dynamometer with

electronic control of power absorption to meet these requirements for

both the new SFTP and current FTP testing, any system would be allowed

that yields equivalent or superior test results.

The improved road load simulation and the new criteria for

allowable speed variation for FTP compliance determination are proposed

to be implemented in the 1998 model year. Manufacturers could elect to

use improved road load simulations prior to 1998, at their option.

The Agency is also proposing a minor procedural change that would

remove the current 5500-pound test weight cap, to be implemented in the

1998 model year with the improved road load simulations.

B. Alternative Approaches

As indicated, EPA is considering a number of alternatives to

critical elements of the central proposal. The following provides a

summary of the most important of these alternatives. A full discussion

of all the options and alternatives considered is found in the Support

Document to the Proposed Regulations for Revisions to the Federal Test

Procedure: Detailed Discussion and Analysis.

In determining compliance with the emission standards, EPA is

considering two alternatives to the proposed FTP/SFTP composite and the

related standards: (1) promulgating three separate sets of standards,

one set each for aggressive driving, post-soak startup emissions, and

A/C impacts; and (2) promulgating a single set of standards, based on a

simple weighted average of separate standards for each control area.

Both of these alternatives would use the same cycles and test

procedures as the composite approach of the central proposal. However,

instead of weighing them with Bag 1 of the FTP and using bag weights to

help establish appropriate compliance procedures and standards, the

alternative approaches would establish emission standards specifically

for each new control area.

The Agency did not select either of these alternatives as the

central proposal because of difficulties encountered in determining the

appropriate amount of in-use compliance margin to allow when

establishing emission standards. Also, the proposed concept of indexing

the SFTP standards to any future changes in FTP standards probably

would not work with either of the two alternatives. If data are

submitted that could help establish appropriate in-use margins, EPA

would reevaluate the most appropriate compliance structure and, if

[[Page 7413]] appropriate, may select one of the alternatives in the

final rule.

The Agency is also considering the alternative of establishing a

single standard for NMHC+NOX, instead of separate standards, and

invites comments on the cost and emission impacts of this alternative.

One issue was identified too late for EPA to properly evaluate it.

Concern was raised that the proposed level of CO control may

significantly interfere with the ability for vehicles to comply with

the proposed level of NOX control. Should further data and

analyses substantiate that tradeoffs between CO and NOX control

would preclude meeting the proposed level of NOX control, EPA

would consider reducing the stringency of the CO standards for the new

control areas in the final rule.

On October 20, 1994, EPA representatives received a joint vehicle

manufacturer proposal from the Ad Hoc Panel that addressed emissions

arising from aggressive driving and A/C operation and proposed emission

standards for each of these two areas. The Agency has not had

sufficient time to fully analyze the concepts offered by the panel or

to incorporate the manufacturer proposal as an explicit, complete

alternative to the primary Agency proposal presented today.

Nevertheless, the manufacturers' specific proposals fall within the

scope of the options and alternatives discussed by EPA in today's

notice. The Agency has submitted materials supplied by the panel on

October 20, 1994, to the rulemaking docket.11 Analysis of these

elements by the Agency, as well as any related material supplied in the

future, will also be docketed. In order that the Agency may make the

most informed and appropriate judgments in any final rulemaking, EPA

encourages interested persons and organizations to evaluate and comment

upon these materials.

\11\Ad Hoc Panel, ``Industry Proposal on FTP Revisions,''

October 20, 1994.

---------------------------------------------------------------------------

In the area of A/C emission control, EPA is considering an

alternative to the proposed test simulation of A/C operation, as well

as the alternative of requiring A/C testing across the cold start (that

is, Bag 1 of the FTP). The alternative A/C simulation would leave the

A/C off in the test cell, but would increase the dynamometer load curve

across the range of vehicle speeds to reflect the additional load

imposed by an A/C compressor during ozone exceedance conditions.12

\12\The Ad Hoc Panel has submitted a proposed methodology for

such a dynamometer simulation of A/C load, dubbed ``Nissan II.''

Manufacturers are pursuing additional refinements to address

potential concerns with the approach, such as the ability to

simulate air compressor cycling and A/C loads at idle, which cannot

be simulated on a dynamometer.

---------------------------------------------------------------------------

In the intermediate soak area, the effect on in-use emissions of

the alternatives depends on future changes to the stringency of the FTP

standards, the control strategies manufacturers would employ to meet

such future standards, and the impacts those strategies might have on

post-soak emissions. Because these are not known, alternatives might

include exemption from aspects of the soak requirement or total

deletion of the soak requirement.

IV. Statutory Authority and Legal Analysis

The promulgation of these regulations is authorized by sections

202, 206, 208, and 301 of the Clean Air Act (CAA or the Act) as amended

by the Clean Air Act Amendments of 1990 (42 U.S.C. 7521, 7525, 7542,

and 7601). Section 206(h) of the Act requires EPA to ``review and

revise as necessary--the testing of motor vehicles and motor vehicle

engines to insure that vehicles are tested under circumstances which

reflect the actual current driving conditions under which motor

vehicles are used, including conditions relating to fuel, temperature,

acceleration, and altitude.'' Congress mandated that EPA exercise its

authority under section 206(a) of the Act, giving broad authority to

determine appropriate test procedures, consistent with the broad

direction of section 206(h), to determine appropriate changes to

reflect real world conditions.

Although the text of the statute and the legislative history do not

provide explicit criteria or intent for this review, EPA believes the

primary concern of Congress is having test procedures for LDVs and LDTs

reflect in-use conditions in order to obtain better in-use emission

control. This flows from the basic purpose of test procedures--to

measure compliance with the emission standards--and from standards

designed to obtain in-use emission reductions. Therefore, EPA made this

the primary concern and objective.

A more detailed analysis of the statute, the scope of EPA's

authority, and interpretation of how best to exercise EPA's discretion

under section 206(h) are found in the Support Document to the Proposed

Regulations for Revisions to the Federal Test Procedure: Detailed

Discussion and Analysis.

V. The FTP Review Project and Areas of EPA Concern

In response to the review requirement of the CAAA, EPA initiated

the FTP Review Project (the FTP Review) in November 1990. The first

action of the project team was to perform an initial review of existing

information to identify elements of the current FTP that might be of

concern (justifying additional focus) and others that might not justify

concern at this time.

Of immediate concern to EPA was representativeness of the driving

cycle used in the current FTP, the ``LA4'' or ``Urban Dynamometer

Driving Schedule,'' especially in the area of aggressive driving

behavior.13 It was clear that the LA4 maximum speed of 57 mph

excluded a significant fraction of higher-speed, in-use

operation.14 Similarly, EPA suspected that an important fraction

of in-use accelerations were more severe than those found in the LA4. A

1990 CARB study found much higher emissions, particularly for CO,

during operation at high acceleration rates relative to those seen

during FTP-level accelerations.

\13\In this report, ``driving behavior'' refers to the

measurable consequences of the operator's action on the accelerator

pedal, including vehicle speed, throttle variation, acceleration,

and power.

\14\Details about the development of the LA4 driving cycle can

be found in an SAE paper, ``Development of the Federal Urban Driving

Schedule,'' Ronald E. Kruse and Thomas A. Huls, EPA, 1973, #730553.

---------------------------------------------------------------------------

One possible explanation for these emission increases is that the

engines were not calibrated for emission control during the higher

engine loads associated with aggressive driving, as these loads are not

encountered during current FTP testing. However, insufficient data

existed at the time to quantify the in-use frequency of aggressive

driving events or the actual emission impacts. There were also

concerns, based on engineering judgment, about other aspects of driving

behavior that were not represented in the current test procedures for

which no data existed. Thus, the Agency concluded that further

information was necessary to properly represent actual driving

conditions. In collaboration with key stakeholders, EPA began extensive

research into driving behavior and conditions and their emission

implications.

During the course of the research a number of other concerns with

the current FTP were identified, including two additional concerns with

the LA4 representation of in-use driving behavior. The first concern

was start driving behavior; that is, behavior immediately following

vehicle startup [[Page 7414]] and initial idle. The LA4 cycle used in

the current FTP brings the most aggressive operation close to the

beginning of the cycle; driving survey data suggest this is atypical of

in-use operation. The second concern was microtransient behavior (rapid

speed fluctuations). In-use driving survey data contains more frequent

speed fluctuations than the FTP.

The Agency identified concerns about four additional elements of

the FTP: The duration of the soaks; the representation of A/C load;

representation of additional loads on the engine due to factors such as

road grade, extra cargo, or trailer towing; and the adequacy of the

dynamometer specification for representation of real road load.

With respect to soaks, EPA sought to determine if significant

levels of emissions are missed by the current FTP because only very

short- and long-duration soaks are reflected in the current structure.

One related hypothesis was that the much faster cooling rate of

catalysts compared to engines might lead to excessive emissions during

intermediate-duration soaks.

Several aspects of the A/C load simulation were problematic. The

current FTP adds load as a percentage of the base road load horsepower

curve, which means the FTP A/C load decreases with decreasing speed,

while real A/C system loads relative to road load horsepower are

highest at low speed. Also, vehicles with different base horsepower

curves end up with different FTP A/C load simulations, even if they

have identical A/C systems. Additionally, the Agency believes that the

current method significantly under-represents the magnitude of in-use

A/C loads. As in the case of aggressive driving behavior, incorrect

representation of A/C loads during the FTP risks incorrect simulation

of the emissions these loads would generate from an engine in-use.

Road grade, vehicle towing, and cargo also represent a load effect

on the engine. The 300-pound passenger-plus-cargo allowance on the FTP

is clearly unrepresentative for some driving situations, especially for

trucks, and the absence of road grade or vehicle towing simulations on

the FTP means these actual in-use loads are not a factor determining

emission standards or compliance with those standards.

Three aspects of the current FTP dynamometer configuration have the

potential to misrepresent the actual road load experienced by vehicles

in-use. First, the shape of the speed/load curve on current

certification dynamometers is fixed and cannot be changed; the

magnitude of the speed/load curve is adjusted by periodically

calibrating the dynamometer at a single speed (currently, 50 mph). As a

consequence, loads at speeds other than the calibration point can be

misrepresented. Second, current FTP dynamometers cradle the vehicle

drive wheels between two small (8.65-inch) rolls. Heating effects and

pinching of the tire result in an unrepresentative simulation of road

``surface.'' Third, the dynamometer rolls are currently uncoupled and

the front roll (which bears the power absorber) spins somewhat more

slowly than the rear (which provides the vehicle speed signal); this

tends to bias the system towards underloading the vehicle.

The Agency analyzed three other elements of the FTP and believes

revising the current procedures is unnecessary at this time. The first

such area was the altitude of testing. Given that EPA has the authority

to perform vehicle testing at any altitude, and it currently exercises

that authority, the Agency is not proposing to supplement by further

regulation the altitude testing flexibility in current law. While it is

possible that driving behavior may differ at high altitudes, EPA

believes that any emission controls required for aggressive driving

will also be effective during high altitude driving.

A second element which EPA did not pursue beyond the initial

evaluation was test fuels. In-use fuels have a wide range of

properties. This specification for fast fuel allowance for a range of

fuels (40 CFR 86.113-94) appear to provide EPA with the flexibility to

use a variety of test fuels ranging from an average in-use fuel to some

of the less typical in-use fuels with qualities that could effect

emissions. Significant differences, with potentially large emissions

implications, do appear to exist between average in-use gasoline and

the gasoline (indolene) typically purchased by both EPA and industry

for certification testing. After evaluating approaches to addressing

this situation, EPA concluded that changes to the regulations are not

necessarily required, since the current regulations provide the

flexibility needed to address those situations where the use of

indolene may not be representative. In addition, various programs to

address in-use fuel qualities are still under consideration. If a

decision is ultimately made to change the certification fuel

regulations, it may be best to do so along with changes to the

specifications for in-use fuels.

Finally, EPA believes that it is unnecessary to further address the

direct impacts of ambient temperature on FTP tailpipe emissions in this

proposal. At the time the Amendments were adopted, the FTP evaluated

tailpipe emissions performance in the midrange of temperature (68 deg.

F to 86 deg. F), but omitted both cold and hot temperature testing. The

emission concern following cold temperature soaks and during cold

temperature operation is increased CO emissions. This concern was

addressed through EPA's Cold Temperature CO rulemaking (57 FR 31888).

The direct emission impact during hot temperature operation is

increased fuel evaporation. Ambient temperature should not otherwise

affect tailpipe emissions, as the engine and combustion temperature are

not affected in any significant way by temperatures hotter than 86 deg.

F. This concern was addressed through the Agency's Evaporative

Emissions rulemaking (58 FR 16002). Ambient temperature also produces

indirect emission effects through increased operation of the vehicle A/

C, affecting the load on the engine. This indirect aspect of

temperature was addressed in EPA's detailed review of the FTP and is

reflected in today's proposal.

The FTP Review project team found that existing information was

clearly inadequate for evaluating potential revisions to the test

procedures. Consequently, a number of new data gathering and analytical

efforts were undertaken in connection with the project. In several of

these efforts, EPA resources were supplemented by significant

cooperative investments from other sources, including the American

Automobile Manufacturers Association (AAMA), the Association of

International Automobile Manufacturers (AIAM), and the California Air

Resources Board (CARB). These studies provided EPA with unprecedented

data on which to base its comparative review with the FTP and to

construct the options presented in today's proposal.

VI. In-Use Behavior

The first critical need in reviewing the FTP was a current database

on in-use driving and vehicle soak behavior. The Agency collaborated

with AAMA, AIAM, and CARB over the spring and summer of 1992 to conduct

surveys of in-use driving and soak behavior in four major U.S. cities.

A. In-Use Driving Behavior

Instrumented vehicle surveys and/or chase car studies were

conducted in Baltimore, Maryland; Spokane, Washington; Atlanta,

Georgia; and Los Angeles, California. In May of 1993, EPA published its

initial conclusions regarding aggressive driving behavior in the

``Federal Test Procedure Review Project: Preliminary Technical

Report.''15 These conclusions were largely based on the Baltimore

instrumented vehicle survey data. Subsequent analysis has found the

larger three-city instrumented vehicle results to be consistent with

the Baltimore-only results. The three-city analysis showed that nearly

13 percent of vehicle operation, on a time-wrighted basis, occurs at

combinations of speed and acceleration that fall outside the matrix of

speeds and accelerations found on the LA4 driving cycle. The maximum

observed in-use speed was 95.5 mph, compared to the LA4 maximum speed

of 56.7 mph, and slightly more than seven percent of in-use vehicle

operation time was spent at speeds greater than 60 mph. Average speed

from the three-city in-use data was 25.9 mph compared to 19.6 mph over

the LA4. [[Page 7415]]

\15\U.S. Environmental Protection Agency, Federal Test Procedure

Review Project: Preliminary Technical Report, EPA 420-R-93-007,

Office of Air and Radiation, May 1993.

---------------------------------------------------------------------------

Specific power is also useful when analyzing aggressive driving

behavior.16 Measures of power also indicated that in-use driving

behavior was more aggressive than reflected in the LA4. Specific power

in the three-city sample ranged up to 723 mph\2\/sec and averaged 47.0

mph\2\/sec. The LA4 has maximum power of 192 mph\2\/sec and an average

of 38.6 mph\2\/sec.

\16\The power needed from an engine to move a vehicle is

proportional to both the vehicle speed and the acceleration rate.

Neither variable, by itself, is a good measure of the load placed on

the engine. The joint distribution of speed and acceleration is

probably the best measure, but it must be examined in three

dimensions, which is difficult to visualize and comprehend. The

concept of specific power provides a two-dimensional measure which

is roughly equal to 2*speed*acceleration and has the units of

mph\2\/sec.

---------------------------------------------------------------------------

The Agency analyzed the in-use survey data to determine how the

above findings on speeds, accelerations, and power measures were

affected by other factors, including vehicle type (car/truck),

transmission type, vehicle performance level, time of day, and day of

the week. The first three vehicle-related factors are reflected in

today's proposal. The discussion of the analysis and findings are in

the Support Document to the Proposed Regulations for Revisions to the

Federal Test Procedure: Detailed Discussion and Analysis and the

Technical Reports.

The Agency also examined start driving behavior as represented by

the instrumented vehicle survey data. The Agency determined that the

start driving (operation following the initial idle and before coolant

temperature exceeded 140 deg. F) in the survey data generally did not

exceed 240 seconds. Further analysis showed that the speeds of start

driving did not change substantially following soaks of different

durations, but they did differ from those found in hot stabilized

driving. The results for in-use initial idle time and start driving are

different than the representation of these elements in the FTP. The LA4

cycle has atypical high speeds over the first four minutes of a vehicle

trip. On the other hand, the LA4 has substantially less aggressive

accelerations than the first 80 seconds or so of typical in-use start

driving, while it is substantially over-aggressive when compared to the

succeeding 160 seconds. For initial idles, the FTP presumes 20-second

durations for both cold and hot starts, whereas the in-use averages

from EPA's data were 28 seconds for cold starts and only 12 seconds for

hot starts.

The previous discussion of in-use speeds and accelerations presents

a snapshot of driving behavior. Although the acceleration measure,

which looks at the change in speed from one second to the next,

partially characterizes the transient nature of driving, other measures

expand the time interval to examine the rapid fluctuations in speed, or

microtransients. One measure, referred to as jerk, is equal to the

change in acceleration. A related measure is the second-to-second

change in specific power. Conceptually, this measure captures the

change in the power requirement imposed by the driving behavior.

The Agency used the three-parameter instrumented vehicle data from

Baltimore, Spokane, and Atlanta,17 to calculate these

microtransient measures for in-use driving behavior and compared the

results to the LA4's representation. The measures of jerk and change in

power are shown in Table 2.

\17\See the Technical Reports for a full description and

analysis of this data.

Table 2.--Measures of Microtransient Driving From Instrumented Vehicle

Data/Sec

------------------------------------------------------------------------

Jerk Change in power

---------------------------------------------------

Mean of the Mean of the

Source absolute Standard absolute Standard

values (mph/ deviation values deviation

sec) (mph/sec) (mph2/sec) (mph2/sec)

------------------------------------------------------------------------

In-use driving...... 0.47 0.89 20.48 34.36

LA4................. 0.36 0.63 14.96 22.96

------------------------------------------------------------------------

For both jerk and change in power, the mean of the absolute values were

used in order to look at both the positive and negative values (the

mean of the signed values of jerk is always equal to zero). The in-use

means were higher than those for the LA4, indicating larger in-use

changes in acceleration and power, as well as reflecting, in part, the

LA4's acceleration rate cutoff of 3.3 mph/sec and the maximum speed of

57 mph. The standard deviations of jerk and change in power are

probably a better measure of microtransient behavior. Again, in-use

data show larger values for both measures. The greater variation around

the mean demonstrated by the in-use data suggests that the LA4 does not

adequately represent the microtransient nature of in-use driving

behavior.

B. Soak Behavior

The survey data were also analyzed to determine the frequencies at

which soaks of different durations occurred in-use. The Agency found

that soaks of less than 10 minutes and greater than 8 hours occur with

the highest frequencies in use. However, EPA also found that a

significant portion of in-use soaks are of intermediate duration. For

example, nearly 40 percent of all soaks in the Baltimore survey data

were between 10 minutes and 2 hours. Given that the current FTP employs

only two soaks (the 10-minute hot soak and the 12- to 36-hour cold

soak) to represent the range of soaks in-use, EPA was concerned that

the current FTP might not adequately control for emissions following

these intermediate-duration soaks.

C. Air Conditioning

A number of variables affect the range of A/C usage, particularly

temperature, sun load, and humidity, all of which [[Page 7416]] vary by

season, time of day, and geographic location. Given that the overall

goal of the Act is to help bring localities and regions into compliance

with the National Ambient Air Quality Standards (NAAQS), the Agency

chose to focus attention on the contribution of A/C to vehicle

emissions during typical high ozone situations. Analyses of ozone

exceedances revealed that ozone exceedances typically occur on days

with a mean ambient temperature of 95 deg.F, 30-40 percent relative

humidity, and limited cloud cover.

In August and September 1994, the Agency conducted an instrumented

vehicle study in Phoenix, Arizona. Preliminary analyses of the survey

data indicate that the average A/C usage was 77 percent for days that

reached a peak temperature between 90 deg.F and 100 deg.F. The A/C

compressor was actually engaged 61 percent of the total time (see

Technical Reports and the Support Document to the Proposed Regulations

for Revisions to the Federal Test Procedure: Detailed Discussion and

Analysis for full analysis). The high use of A/C in ozone exceedance

conditions makes the accurate simulation of A/C during the FTP more

important.

D. Additional Elements Affecting Engine Load

A comprehensive evaluation of additional elements affecting engine

load would require surveys of the frequency of occurrence of the

elements in-use, as well as evaluation of interactive effects with

driving behavior. For road grade, a 1980 EPA report18 indicated

that positive road grades average 1.66 percent nationally and that

roughly six percent of national VMT is spent on grades of four percent

or higher. The Agency sought to supplement this information with

driving behavior data over road grade, gathered during the chase car

portion of the in-use driving surveys. Unfortunately, problems with

noise and insufficient resolution on the measure of grade rendered the

data inadequate, and no alternative data source was available. In

addition, EPA was unable to conduct in-use surveys in the areas of

passenger/cargo loading and trailer towing, due to the scope and nature

of the necessary survey instrument. As a consequence, EPA has

insufficient data for use in evaluating the additional elements

affecting engine load that were originally identified as areas of

concern.

\18\18 U.S. Environmental Protection Agency, Passenger Car Fuel

Economy: EPA and Road, EPA# 460/3-80-010, September 1980, p. 119.

---------------------------------------------------------------------------

VII. Representative Driving Cycles

In order to evaluate the emission impacts of in-use driving and

soak behavior, EPA designed three driving cycles that were

representative of the in-use survey results, using segments of actual

in-use driving survey data. Concurrently, EPA determined weighting

factors to reflect the fraction of in-use operation represented by each

cycle; these factors are used to properly weight the emissions from the

cycles when doing an emission assessment.

The Agency developed separate cycles for start driving and

aggressive driving. The Agency chose to develop individual cycles

rather than a single ``representative'' cycle in order to evaluate

EPA's areas of concern independently. This is most critical in the case

of aggressive driving where both capturing the diversity of aggressive

driving behavior and representing it proportionally in a single cycle

covering all in-use operation would lead to a very long cycle.

The Start Cycle (ST01) represents three successive 80-second

segments of in-use driving immediately following the initial idle.

Testing using ST01 allowed separate determination of start driving

emissions; ST01 was also used to quantify the emissions effects of

varying soak duration.

The second cycle, characterizing aggressive driving, was the

Representative Non-LA4 Cycle (REP05). This cycle targeted speeds and

accelerations, as well as microtransient effects, not covered by the

current LA4.

To complete the representation of in-use driving behavior for

emission assessment purposes, a third cycle, the Remnant Cycle, was

developed to characterize in-use driving behavior not represented by

either the ST01 or REP05.

The Agency used the same basic cycle development methodology for

each of the three representative cycles. A full discussion of the

methodology used, the composition of each cycle, and how it compares to

the cycle in the FTP is found in the Technical Reports.

It seemed clear from the in-use survey data that rapid speed

fluctuations, including ones not well represented on the LA4, could be

found in all types of in-use vehicle operation. The Agency's use of

actual microtrips as the building blocks for the three representative

cycles directly incorporated such microtransient driving behavior into

all three cycles.

The Agency has assumed that driving behavior is not affected

significantly by A/C operation and that the representative driving

cycles developed from the in-use driving survey data are equally

applicable to testing with the A/C system on and off. In fact, even

though the Atlanta driving survey was the only one of the three surveys

conducted during the summer, that city had the most aggressive driving

of the three cities. Thus, it does not seem likely that A/C operation

could have a significant impact on driving behavior. Nonetheless, the

Agency welcomes data and comments on the relationship between A/C

operation and driving behavior.

VIII. Emission Inventory Assessments

An assessment of emissions from four areas for potential emission

control was conducted using the representative test cycles developed

from the survey data. A full description of the test programs and the

results can be found in the Technical Reports. The following summarizes

the conclusions for each area considered.

A. In-Use Driving Behavior

The FTP Review's emission assessment of in-use driving behavior was

based on a vehicle emission test program conducted cooperatively by

EPA, CARB, AAMA, and AIAM during 1993 and early 1994 (referred to

subsequently as the Non-LA4 Emissions Test Program).19

\19\EPA's assessment was limited to EPA's and AAMA/AIAM data.

Due to differences in testing hardware, CARB's emission results were

not directly comparable.

---------------------------------------------------------------------------

On the basis of the EPA data, the project team concluded that the

LA4 under-predicts actual in-use hot stabilized emissions by 0.043 g/mi

NMHC, 2.8 g/mi CO, and 0.083 g/mi NOX on current technology,

properly operating vehicles.20 These numbers do not have any

direct bearing on the FTP standards; they are simply an estimate of the

additional amount such vehicles actually emit in-use, compared to the

FTP test results.

\20\These estimates are only for the emission under-prediction

related to driving behavior. Other factors such as soak are

addressed in the sections to follow.

---------------------------------------------------------------------------

Table 3 shows the percentage contribution to the in-use emission

increase from the Start (ST01), Remnant, and aggressive (REP05) driving

cycles, weighted by their respective proportion of in-use driving. As

expected, the aggressive driving of REP05 contributed significantly to

the difference. More surprisingly, however, significant contributions

to the increase also came from the Start and Remnant Cycles,

particularly for NMHC and NOX.

[[Page 7417]]

Table 3.--Contributions to the In-Use g/mi Increase by Three Types of

Driving

------------------------------------------------------------------------

Driving NMHC CO NOX

------------------------------------------------------------------------

All (In-Use Increase)............ 0.043 g/mi... 2.784 g/mi 0.083 g/

mi.

Start............................ 30.2%........ 17.1%..... 23.0%.

Remnant.......................... 33.8%........ 25.0%..... 45.6%.

Aggressive....................... 36.0%........ 57.8%..... 31.4%.

------------------------------------------------------------------------

The AAMA/AIAM portion of the program was conducted in late 1993 and

early 1994. This 26-vehicle, 8-manufacturer program included hot

stabilized testing with REP05, the 505, and the 866, but none with the

Remnant or Start Cycles; thus, a complete assessment of in-use hot

stabilized driving could not be conducted with the manufacturers' data.

Nevertheless, comparisons were made between the EPA and manufacturer

program results for REP05 as well as the difference between REP05

emissions and hot stabilized LA4 emissions. In looking at the emission

difference between REP05 and hot LA4, the LDV and light light-duty

truck (LLDT) average for the EPA tested vehicles was 0.04 g/mi while it

was 0.06 g/mi for the vehicles tested by the manufacturers. The CO

emissions tracked better, with the REP05 and hot LA4 difference of 5.71

g/mi for EPA and 5.32 g/mi for the manufacturer tests. The manufacturer

testing showed a much larger NOX differential. The NOX

difference between REP05 and hot LA4 was 0.25 g/mi for the

manufacturers' testing while only 0.09 g/mi for EPA testing. The NMHC

and CO differences are primarily among the LLDTs while the NOX

difference was found in LDVs and LLDTs. The Agency did not test any

heavy light-duty trucks (HLDTs); however, the manufacturers' results

showed these vehicles as having the largest grams per mile increases

from hot LA4 to REP05. This comparison suggests that EPA's emission

assessment should provide a reasonable, if not conservative, estimate

of in-use emissions.

B. Intermediate Soaks

The Agency conducted the assessment of in-use emissions following

intermediate soaks using data from EPA's Soak/Start Test Program,

conducted in two phases between July 1993 and June 1994. The testing

represented the soaks observed in the driving survey data. The primary

cycles used to measure post-soak emission levels for the emission

assessment were variations of EPA's representative Start Cycle (ST01).

Post-soak emissions in the Soak/Start Test Program, measured over

the ST01 cycle, increased steadily and sharply as soak duration was

incremented between 10 minutes and 60 minutes. The average ST01

emissions for all vehicles tested for NMHC, CO, and NOX were

higher following the 60-minute soak than they were for the 10-minute

soak by factors of seven, two, and four, respectively. The increases

were significant in absolute terms as well; for example, the average

NMHC emissions on three Tier 1 vehicles went from about 0.05 g/mi

following the 10-minute soak to over 0.50 g/mi following the 60-minute

soak. The rate of increase moderated with soaks longer than 60 minutes,

such that emissions of all constituents following a 2-hour soak were

within 50 percent of cold soak levels. The subset of Tier 1 vehicles in

the EPA program showed similar percentage increases as a function of

soak duration relative to the Tier 0 vehicles, although the average

emission levels of these vehicles were lower than the Tier 0 vehicles.

C. In-Use Air Conditioner Operation

The Agency conducted three test programs and participated

cooperatively with AIAM and AAMA in an additional test program during

late 1993 and early 1994 with the purpose of assessing in-use emissions

due to A/C operation. Detailed descriptions of all of these programs

and the results are contained in the Support Document to the Proposed

Regulations for Revisions to the Federal Test Procedure: Detailed

Discussion and Analysis.

The first test program compared emissions during the current FTP A/

C simulation to emissions obtained with the A/C actually operating and

confirmed that the current A/C simulation method significantly under-

represents the actual load of the A/C on the engine.21

\21\In fact, the Agency believes that the effect on emission

values of the additional ten percent dynamometer road load

horsepower is negligible and unobservable within the range of

current test-to-test variability.

---------------------------------------------------------------------------

The second test program went beyond the current FTP by testing A/C

impacts over the three representative cycles (REP05, ST01, Remnant) as

well as over the LA4. As in the first program, results from this

testing demonstrated an overall increase in actual emissions with the

A/C operating. In particular, the magnitude of the NOX increase in

both programs was much larger than expected and caused the Agency to

focus further research and analysis on the effects of A/C operation on

NOX emissions.

The third test program was very similar to the second but was

designed to collect second-by-second emissions and vehicle operating

data. Analysis of these data indicated that the significant A/C-related

emission impacts were occurring during idles and accelerations; on the

LA4, ST01, and Remnant cycles the combination of idles and

accelerations accounted for more than 80 percent of the total observed

NOX increase. As was the case in the previous program, the overall

increases in NOX were heavily weighted towards the moderate and

lower speed driving of the ST01, Remnant, and LA4 cycles, although some

increases were seen on the REP05 cycle.

A detriment of these test programs is that they did not adequately

or fully represent the actual conditions under which A/C systems are

likely to be operated. To test vehicles under an accurate simulation of

environmental conditions and vehicle speed, an emission testing program

(referred to as the AC Rochester [ACR] test program) was conducted by

vehicle manufacturers in a sophisticated environmental test

facility.22 The Agency and manufacturers cooperatively defined for

the testing a set of environmental and meteorological parameters to

represent a typical ozone nonattainment day.

\22\This program was developed as a cooperative effort between

EPA and manufacturers with funding from manufacturers.

---------------------------------------------------------------------------

Eight vehicles certified to the EPA's Tier 1 emission standards

with HFC-134a A/C refrigerant systems were tested in the program. Once

again, the effects of A/C operation were most pronounced on the

moderate-to-lower speed cycles. On a hot, stabilized LA4, the average

increases were 0.011 g/mi for NMHC, 0.3 g/mi for CO, and 0.205 g/mi for

NOX. The increases observed on the REP05 cycle were smaller than

on the LA4, but still noteworthy due to the performance of several of

the vehicles, causing the Agency some concern about the impact of A/C

operation during aggressive driving behavior. Fuel economy decreased by

about 13 percent on the REP05 with the A/C operating, substantially

less than the 20 percent reduction on the LA4, further indicating that

the A/C load as a proportion of total load tends to diminish as speeds

and accelerations increase. [[Page 7418]]

D. Additional Elements Contributing to Engine Load

As part of the Non-LA4 Emission Test Program, EPA conducted an

evaluation of emission impacts from road grade by simulating a two

percent grade through increased inertia weight at the dynamometer

during testing of three vehicles over the three representative cycles.

The road grade effect, weighted by the percentages of the driving types

in-use, showed a consistent HC increase of 0.04 g/mile, a highly

variable CO increase averaging 3.2 g/mile, and a NOX increase (due

largely to one vehicle) of 0.19 g/mi. Due to the absence of

comprehensive in-use survey information, EPA did not calculate

adjustments to these numbers to reflect in-use frequency of grade or

modifications to driving behavior over grades.

IX. Cause and Control of Emissions

Three candidate areas for emission control are aggressive driving

behavior, intermediate soak periods, and A/C operation. Microtransient

driving behavior carries over and is addressed withing these candidate

areas. The following discusses each of these areas, the causes of

emission, and potential strategies for controlling the emission.

A. Aggressive Driving Emissions

Both agencies and the vehicle manufacturers anticipated that a

primary cause of higher emissions during aggressive operation would be

``commanded enrichment,'' which is done by programming the vehicle's

computer to change the air/fuel ratio to the rich side (more fuel for

the same air) of stoichiometric operation, typically in response to

high loads on the engine. Aggressive driving, positive road grade,

increased vehicle loading, and air conditioning operation all generate

increased load on the engine. Further, the effect of these factors are

cumulative. Manufacturers currently employ commanded enrichment in

essentially all applications when high load at the engine (regardless

of the source) is detected, both to provide increased power and to cool

the engine or catalyst.

Using data from EPA's Non-LA4 Test Program, supplemented by AAMA/

AIAM data,23 the Agency concluded elevated HC and CO emissions

during aggressive driving are due primarily to enrichment, both

commanded and transient. High NOX emissions during aggressive

driving, EPA believes, are due both to an increase in engine out

NOX (from higher temperatures) and to relatively poor catalytic

conversion. Poor catalytic conversion is due to lean events resulting

from erratic A/F control and to an A/F control strategy which is not

biased rich. The Agency also recognizes that catalyst breakthrough is a

potential contributor to CO and NOX emissions during aggressive

driving.

\23\AAMA/AIAM spotlighted commanded enrichment by retesting a

portion of the vehicles in their test program in a stoichiometric

configuration, as well as in the ``production'' configuration and

provided second-by-second data acquisition capability for emissions

and a variety of engine and emission control parameters, allowing

fine scrutiny of individual driving events.

---------------------------------------------------------------------------

The Agency considered five strategies that manufacturers might

employ for addressing the causes of high emissions from aggressive

driving: improved control of the A/F ratio (fuel control) through

calibration; improved fuel control by upgrading fuel injection systems

to sequential firing; upgrading to electronic throttle control;

improvements to catalyst design; and reapplication or refinement of

conventional NOX emission control systems. These strategies are

discussed in detail in the Technical Reports.

Of these strategies, the various recalibration options appeared to

be the least costly, because each of the remaining strategies involved

per-vehicle hardware modifications. In addition, data from the Non-LA4

test program indicated that recalibrations would probably control the

vast majority of aggressive driving emissions.

B. Intermediate Soak Periods

The Agency examined the causes of post-soak emissions using data

from the EPA Soak/Start Test Program and a preliminary program called

the Albany Cooldown Study that gathered real-world engine and catalyst

cooldown profiles. The data from these programs indicated that

increased emissions following intermediate soaks arise in three ways:

Rapid catalyst cooldown following keyoff,

Slow catalyst thermal recovery following a restart, and

Manufacturer calibration strategies in response to the

startup condition.

The Agency data indicate the catalyst cools to below the

temperature needed to sustain significant catalytic activity (``light-

off'' temperature) within 20-30 minutes of vehicle shutoff, while the

engine is still near its normal operating temperature. Data also

indicated a significant delay in achieving light-off temperature upon

restart, apparently due to the cool initial temperature of the engine-

out exhaust. Because tailpipe emissions increase dramatically when the

catalyst is below light-off temperatures, the relatively long delay in

achieving light-off results in disproportionately high emission

increases over intermediate soaks.

The current FTP provides no incentive for manufacturers to retard

the rapid cooldown of the catalyst during intermediate soaks. In

addition, testing found differences in engine-out emissions determined

by the manufacturer's calibration strategy upon restart. Following

intermediate-duration soaks, one vehicle had a lean calibration

strategy which increased NOX emissions. Here again, the test

results indicate that significant emissions may be occurring in-use

because of a lack of incentive for manufacturers to optimize startup

calibrations following intermediate soaks.

In general, strategies for reducing post-intermediate soak

emissions are catalyst-based and either focus on the retarding of

catalyst cooldown through insulation after the vehicle is shut off or

the enhancement of catalyst light-off upon restart.

Of the potential approaches considered for control of intermediate

soaks, EPA is focusing on catalyst insulation as the primary control

strategy. Use of insulation results in greater emission reductions over

intermediate soaks than strategies which focus on improving catalyst

light-off through conventional means and provides more cost-effective

emission benefits than advanced cold start approaches. Although

intermediate soak emissions will likely be reduced to some extent due

to directional improvements in cold start performance, EPA believes

that on Tier 1 vehicles intermediate soak emissions will continue to be

relatively significant because the primary cause of intermediate soak

emissions--rapid cooling of the catalyst--will remain unaddressed.

Because insulation directly addresses catalyst cooldown, EPA

anticipates that this approach will incur significant emission

reductions over intermediate soaks on Tier 1 vehicles, including those

which will incidentally reduce intermediate soak emissions through

improved cold start performance.

C. Air Conditioner Operation

The Agency focused on the NOX impacts from A/C use because of

the large observed increases. The increases in tailpipe NOX with

the A/C operating seen in the ACR Test Program could clearly be linked

to large increases observed in engine out NOX, which are probably

caused primarily by higher combustion temperatures due to the

additional load of the A/C system. Tailpipe NOX can be improved by

[[Page 7419]] increasing NOX conversion efficiency in the catalyst

or decreasing engine out NOX. Control strategies include improving

control of the A/F ratio, eliminating the lean-on-cruise calibration

strategy, adjusting spark timing, adding or enhancing EGR systems

strategic cycling of the A/C compressor, and improving catalysts to

enhance NOX conversion efficiency.

The testing at ACR confirmed that HC and CO were also impacted by

A/C operation. The Agency believes that these HC and CO increases are

related to the increased load on the engine triggering additional

periods of commanded enrichment when the A/C is on. The Agency believes

that the control strategies for HC and CO discussed in ``IX.A.

Aggressive Driving Emissions'' will eliminate HC and CO emissions

increases due to A/C operation as well as during aggressive driving.

X. Options Considered and Information Needed

The following outlines the options which EPA has considered in

developing today's proposal and issues on which more information is

needed. As has been indicated, EPA and other stakeholders conducted

extensive research and examined many options. While today's proposal

selects the approach EPA felt would provide the most emission benefits

feasible, in developing the final rule EPA will reconsider each of the

options in terms of new research and data submitted. The Agency

welcomes comments and additional data on these and any other points. A

full discussion of these issues and a detailed analysis of each option

is found in the Support Document to the Proposed Regulations for

Revisions to the Federal Test Procedure: Detailed Discussion and

Analysis.

A. Affecting Aggressive Driving Cycle

The Agency evaluated three basic options for establishing standards

and vehicle testing aimed at controlling emissions from aggressive

driving. Two options were based on emission performance standards with

compliance measured using a test cycle, and one option was based on a

performance standard using the A/F ratio with a related test procedure.

The Agency was guided by seven criteria in evaluating the options.

First, EPA sought an option that would lead to control of emissions

over the broad range of aggressive driving behavior found in the in-use

driving survey data. Second, due to the non-linear nature of HC and CO

emission increase during enrichment, a high priority was to ensure

sufficient content from the highest-emission operating modes to prompt

manufacturers to employ appropriate control strategies, including

curtailing commanded enrichment. Third, the Agency sought consensus

with CARB, to avoid duplicate or incompatible test requirements.

Fourth, EPA sought to reasonably account for technical concerns raised

by vehicle manufacturers, particularly manufacturer comment on the

necessity of some commanded enrichment events to avoid elevated

catalyst temperature levels from in-use operation leading to catalyst

deterioration.24 Fifth, EPA sought to pursue cost saving elements

like reduction in test time where practical. Sixth, the Agency sought

practical control of microtransient behavior, a candidate area of

control that spans all driving. Finally, EPA favored strategies to

control aggressive driving emissions that would also address the

potentially significant (but unquantified) emissions from other engine

load factors like road grade.

\24\The relationship between curtailing commanded enrichment and

catalyst deterioration is addressed in the discussion of feasibility

in the Technical Report.

---------------------------------------------------------------------------

A full analysis of each option, how it was evaluated, how the level

of emission control was determined, and the feasibility of the approach

is in the Support Document to the Proposed Regulations for Revisions to

the Federal Test Procedure: Detailed Discussion and Analysis and

Technical Reports and comment on the analysis is welcome. Comment is

specifically solicited on the following items:

Comment is requested on the need to allow some commanded

enrichment events during the USO6 Cycle to avoid elevated catalyst

temperature levels from in-use operation leading to catalyst

deterioration.

The Agency is proposing that US06 HC and NMHC emissions be

controlled to the same gram-per-mile emission levels currently achieved

on the second bag of the FTP. US06 CO and NOX emissions are

proposed to be controlled to overall FTP emission levels. These

proposals are based upon the Agency's analyses of the potential control

technology and their related costs and emission reductions, which are

described in detail in the Technical Reports. Comments and additional

data addressing these proposed levels of control are solicited.

Additional information and data are also requested about the potential

tradeoffs between NOX and CO control during aggressive driving,

and on the impact such tradeoffs could have on the appropriate level of

CO control.

Although concern has been expressed that removal of

commanded enrichment could impose a 2 percent to 10 percent power

penalty, EPA believes power enrichment would not be precluded outright

by this proposal, but rather curtailed only within the durations and

speed-acceleration combinations found in the US06 cycle. Thus, the

Agency has concluded on the basis of available data that compliance

with the US06 standard should have a negligible effect on vehicle

performance. Additional data on the effect on vehicle performance under

this proposal is requested.

The Agency has proposed adjustments to the US06 for all

HLDTs and some LDVs and LDTs. These include a change in determing

inertia weight for HLDTs, dynamic load adjustment for low-performance

vehicles, and demonstration of stoichiometric control for wide-open

throttle events for high-performance vehicles. Comments and data are

solicited on the appropriateness of these adjustments and of the

weight-to-power cutpoints. Of special concern is the possible unfair

advantage the proposed high performance cut-off may provide to vehicles

in the 18-21 W/P range.

The Agency has proposed a W/P-based measure for the

performance cutoffs after also considering the alternative performance

criteria based on a vehicle's acceleration time from zero to 60 mph.

The Agency rejected the zero to 60 time approach on the basis of

practical problems related to establishing appropriate cutoff points

and a standardized procedure for determining zero to 60 times. The

Agency solicits comments on the proposed method for making vehicle

performance adjustments, as well as input on alternatives, including

the one discussed above.

B. Affecting Start Driving Cycle and Intermediate Soak

The compliance program approach evaluated for intermediate soaks

and start driving was an emission performance standard applied to the

results of testing over an emission control cycle following a soak

period of intermediate duration. As with control program approaches for

aggressive driving emissions, EPA believes that an emission performance

standard provides the most direct method of controlling the emissions

arising during the particular type of vehicle operation. Given the

particular causes of high emissions in this case, use of design

standards or system performance [[Page 7420]] standards would be

particularly complex and restrictive of the manufacturers' options.

The Agency developed a new Start Control Cycle (SC01) to be used

for controlling emissions following intermediate soaks. Initial idles

and start driving are addressed in SC01 by incorporating the EPA Start

Cycle (ST01) in its entirety. The balance of SC01 is composed of two

microtrips of moderate driving, selected from the in-use survey

database in order to bring the total distance of the new control cycle

up to match the 3.6-mile distance of the 505 Cycle; the resulting cycle

is 568 seconds long.25, 26

\25\The severity of one SC01 acceleration was artificially

modified to be less severe than in the original microtrip. This

preserved the design objectives of matching the 505 trip distance

and reflecting moderate, rather than aggressive driving. The

representative level of microtransient behavior in the cycle was

unaffected by this change.

\26\Analysis of the two microtrips used to complete SC01 shows

higher power levels than the comparable portion of the 505. The

Agency plans to replace these microtrips with those which match

power levels of the 505 more closely. The completed cycle, known as

SC02, will replace SC01 and serve the same purpose.

---------------------------------------------------------------------------

A full analysis of the approaches and issues considered, how each

was evaluated, how the level of emission control was determined, and

the feasibility of the proposed approach is in the Support Document to

the Proposed Regulations for Revisions to the Federal Test Procedure:

Detailed Discussion and Analysis and Technical Reports and comment on

the analysis is welcome. Comment is specifically solicited on the

following items:

The Agency believes that manufacturers should be able to

control emissions on the SC01 cycle following a soak of from 10- to 60-

minutes to the same gram-per-mile emission levels currently achieved on

the third bag of the FTP. Comment on the appropriateness of this level

of standard and method for determining compliance is requested.

The Agency believes that internal catalyst insulation does

not pose a temperature-based feasibility problem for underbody

catalysts.27 However, EPA had insufficient data to reach a firm

view on this issue for the small number of Tier 1 vehicles which might

need to insulate close-coupled catalysts. Thus, EPA solicits comments

or data on the temperature-based feasibility of insulation for close-

coupled catalysts.

\27\Per vehicles with both under-body and close-coupled

catalysts, EPA anticipates that only the underfloor catalyst would

need to be insulated.

---------------------------------------------------------------------------

The Agency believes that application of catalyst

insulation as a strategy for control of emissions following

intermediate soaks is feasible. Data and comments are solicited on the

feasibility of catalyst insulation and its impact on catalyst operation

and durability.

Comments are solicited on strategies to mitigate

temperature increases in the catalyst brought about by insulation (such

as moving the catalyst further downstream and subsequently conserving

exhaust heat ahead of the catalyst to not impair cold start

performance, or switching to more temperature-resistant noble metals

like palladium), as well as spinoff effects of such strategies.

The Agency believes it is necessary to move forward with

an intermediate soak standard either if a significant proportion of

vehicles are certified to Tier 1 standards for a significant time

period following implementation or if it is cost effective and feasible

to pursue control over intermediate soaks on vehicles certified to the

lower standards. The Agency requests comment on the issues of cost-

effectiveness and feasibility of an intermediate soak requirement on

vehicles certified to lower emission standards.

Criteria are being considered to permit manufacturers to

forego the data submittal requirement for SC01 testing following a 60-

minute soak on an engine family basis, allowing manufacturers to reduce

the SFTP soak duration to 10 minutes. Under this option, manufacturers

would be allowed to submit a technical justification demonstrating that

an engine family would clearly pass the intermediate soak requirement.

The Agency solicits comment on this option and potential criteria for

granting such a waiver.

C. Affecting Air Conditioner Operation

The Agency analyzed several possible approaches to compliance

testing designed to control emissions due to

A/C operation. These options hinged on determination of two important

elements--the choice of a control cycle and the choice of a methodology

for simulating A/C operation over that cycle. The Agency pursued a

control program for A/C-on emissions that utilized an emission

performance standard rather than other control options.

A full analysis of each option considered, how it was evaluated,

how the level of emission control was determined, and the feasibility

of the approach is in the Support Document to the Proposed Regulations

for Revisions to the Federal Test Procedure: Detailed Discussion and

Analysis and Technical Reports and comment on the analysis is welcome.

Comment is specifically solicited on the following items:

The control cycle for A/C-related emissions being proposed

is the 866 plus SC01. While the Agency believes these are the best

cycles for A/C control, comments are solicited on the possibility of

substituting the 505 component of the LA4 for SC01. Comments are also

solicited on whether full A/C simulation should be added to the US06

cycle.

A cold start test is not included in today's proposal, but

the Agency does believe that it may be appropriate to return to this

issue with respect to future technologies and future test procedures

and emission standards. The Agency specifically solicits comments on

this issue.

Independent from determining the appropriate control

cycles for testing, the Agency evaluated three principle options for

simulating A/C operation on a given test cycle.28 The Agency

requests comment on the potential applicability of each option and the

various methods of implementing each option, whether any specific

method should be retained as an option in the final rule to allow for

its future development and use by petitioning for Agency approval. The

``Nissan-II'' approach is currently being evaluated by a consortium of

auto manufacturers and the Agency expects to review and evaluate the

data as soon as it becomes available. The Agency specifically requests

comments and data that would allow a better evaluation of this approach

and its viability, as well as suggested improvements that would

alleviate the Agency's concerns, as detailed in the Support Document to

the Proposed Regulations for Revisions to the Federal Test Procedure:

Detailed Discussion and Analysis.

\28\The three options--bench testing, dynamometer simulation,

and running test with A/C on--are discussed in more detail in the

Support Document to the Proposed Regulations for Revisions to the

Federal Test Procedure: Detailed Discussion and Analysis and the

Final Technical Report on Air Conditioning for the Federal Test

Procedure Revisions Notice of Proposed Rulemaking U. S.

Environmental Protection Agency.

---------------------------------------------------------------------------

The Agency has estimated that vehicles can maintain

existing NMHC and CO emission levels with the A/C turned on. For

NOX, the Agency believes that 25 percent of the NOX increase

with the A/C engaed is likely to be unavoidable without increasing the

stringency of the current NOX standard, but is proposing to

control the other 75 percent. The Agency requests comments on the

feasibility of this proposed level of control and the technology

implications of controlling to this level.

[[Page 7421]]

D. Affecting Whole Proposal

The Agency evaluated four different options to translate the

proposed level of emission control for US06, intermediate soak, and A/C

into compliance procedures and appropriate emission standards. The

first option would set stand-alone standards for each control area.

Compliance procedures and standards would be established individually

for aggressive and microtransient driving behavior, A/C, and

intermediate soaks. The second option would combine the three non-FTP

areas of control into a single standard. The third option would

establish a composite standard based on results drawn from both the

SFTP and the FTP. While the basic concept is similar to the second

option, the approach is specifically structured to directly implement

the proposed level of control for each area using bag weights and to

preserve the existing FTP compliance margins. The fourth option

considered by EPA would replace the current FTP with an entirely new

FTP that reflects, as accurately as possible, actual driving behavior.

A full analysis of each option, how it was evaluated, and the

feasibility of each approach is in the Support Document to the Proposed

Regulations for Revisions to the Federal Test Procedure: Detailed

Discussion and Analysis. Comment on the analysis is welcome. Comments

are specifically solicited on the following issues which relate to all

cycles in the SFTP or changes to the FTP.

Use of a composite non-FTP emission standard was chosen as

the central approach chosen instead of using individual stand-alone

standards, a single combined stand-alone standard, a replacement FTP,

or some other option not considered. Stand-alone standards or a single

combined stand-alone standard were not chosen primarily because of the

lack of data to determine appropriate compliance margins and the

difficulty in determining a single emission level given the disparity

in emission levels from vehicle to vehicle. Replacing the current FTP

at this time was not chosen primarily because revising the existing FTP

would potentially impact the stringency of more stringent emission

standards currently being considered for different parts of the

country, such as the California LEV and ULEV standards, efforts by the

Northeast states to adopt California requirements, and voluntary 49-

state emissions standards (``FEDLEV''). Additional information and data

are requested on the use of any of these approaches. Comments

concerning stand-alone standards, or the simple average of the

composite standards, should include consideration of how to set

appropriate standards for both intermediate and full useful

life.29 Durability procedures for new stand-alone standards should

also be addressed.

\29\Tier 1 standards were set for two points in the useful life

of a vehicle--50,000 miles (intermediate) and 100,000 miles (full).

---------------------------------------------------------------------------

Because replacing the FTP would offer better assurances of

in-use emission control and would simplify the test procedure, EPA

believes it makes sense in the long term to consolidate all the test

requirements into a revised FTP. However, to avoid jeopardizing work on

more stringent emission standards and to avoid delaying implementation

of today's proposal, EPA believes it is better to incorporate

consolidation of the FTP with future consideration of tighter federal

standards. Comments are solicited on when consolidation should occur.

Under the non-FTP composite approach, the bag weights for

each cycle are selected to mirror the proposed level of control

determined using the in-use driving survey data. (A discussion of the

proposed level of control for each pollutant and how it was determined

can be found in the Final Technical Report on Aggressive Driving

Behavior for the Revised Federal Test Procedure Notice of Proposed

Rulemaking). Comments are requested on the method used to select each

weighting factor or the weighting given to each bag when determining

compliance with the composite non-FTP emission standards.

Emission standards are proposed to be set at current Tier

1 FTP levels, with an adjustment made for NOX, and are tied to

future changes in the FTP standards. Comments on tying the non-FTP

composite standards to FTP standards, the method used for determining

the standards, the NoX adjustment provided, or the need for other

adjustments are requested.

The Agency considered separating LDVs and LDTs but

determined driving behavior was similar between these classes. Some

adjustments are provided in the proposal for specific vehicle types,

transmission types, and performance rating. Comments on the method used

for determining these adjustments, the need for other adjustments, or

other related issues are welcome.

Very little emission data currently exists on emission

impacts using fuels other than gasoline during the SFTP. Because of

this, EPA considered exempting alternative- and/or diesel-fueled

vehicles from the SFTP requirements, but decided such vehicles would be

able to comply. Information and data related to applying today's

proposal to alternative- and diesel-fueled vehicles are welcome.

The Agency is asking for comments on whether or not it

would be appropriate to establish a single NMHC+NOX standard for

stand-alone A/C or soak/start requirements or for the proposed

composite standards. Comments are also solicited on both the potential

emission impacts and cost implications of this proposed alternative.

Comments are requested on the benefits and feasibility of

the proposed phase-in schedule from MY1998 to 2001. The Agency is

particularly interested in data and comments on how potential concerns

with higher catalyst temperatures should influence lead time, as well

as how these concerns should be balanced with the objective to obtain

the emission benefits under this rulemaking as quickly as possible. If

it appears that wholesale elimination of commanded enrichment with

short lead time could introduce unanticipated problems with catalyst

deterioration, EPA may elect to spread the implementation of the

requirements over a longer period in the final rule. Another option

might be to set an intermediate standard level for the initial phase-

in. Comments are solicited on the relative benefits and costs of an

intermediate standard compared to a phase-in directly to the final

standards.

Today's proposal provides two blanket, automatic

substitutions from the SFTP to the FTP to reduce testing costs and time

for manufacturers. No substitution of FTP bags into the SFTP

calculation is allowed. Flexibility in preconditioning is also provided

in the proposal. If stand-alone standards are promulgated, EPA is

considering an exemption from the intermediate soak requirements.

Comments on any of these aspects or related matters are requested.

Today's proposal will improve the accuracy of the

dynamometer simulation of actual on-road operation during vehicle

testing. In addition, the change in dynamometers to improve accuracy

also allows modifying the equivalent test weight requirements to remove

the cap. Comments are solicited on these changes.

Comments are specifically solicited on the need for

additional lead time to implement the new road load requirements in

terms of the dynamometer changes. If data and additional information

submitted supports longer lead times, the Agency may elect to phase in

the FTP under the same phase-in schedule used for the new SFTP

requirements. Under this alternative, any engine family included in the

SFTP phase-in would also use the improved road load simulations for FTP

testing. To minimize the laboratory burden of maintaining two different

sets of dynamometers, EPA would like to couple any phase-in of the new

road load requirements with procedures allowing an electric dynamometer

to simulate the existing dynamometer load. Comments addressing new road

load lead time should also comment on how such a simulation could be

incorporated.

Changes to allow ``appropriate'' throttle action and new

speed tolerance criteria are included in today's proposal. For each

test cycle, a range of acceptable speed variation is created using the

DPWRSUM30 variable. Each driving cycle has a unique value of

DPWRSUM, which is compared to the DPWRSUM calculated from the driver's

trace (what the vehicle actually drove) to determine a valid test.

Comments are solicited on these aspects of today's proposal,

specifically on the proper method for setting the lower DPWRSUM

threshold for a valid test. [[Page 7422]]

\30\DPWRSUM is the sum in the change in power, a statistic which

is derived from the vehicle speed.

---------------------------------------------------------------------------

XI. Environmental and Economic Impacts

To estimate the emission reductions associated with the proposal,

the expected lifetime emission reductions were determined per vehicle

sold after implementation of the proposed regulations. Baseline

emissions are taken from the extensive test programs conducted by the

Agency and the original equipment manufacturers in support of the FTP

Review Project, as discussed earlier. The weighted averages of the

emission results of these test vehicles over the various new test

procedures constitute the baseline emissions used in this analysis.

A. Emission Reductions

The emission reductions used in this analysis were calculated by

subtracting the proposed level of control for each control area from

the baseline test vehicle emissions. These test vehicle reductions were

then weight averaged to simulate the reductions associated with the

actual in-use vehicle fleet mix. It should be noted that the test

results were derived for an average vehicle with a 50,000 mile catalyst

and do not include any allowance for in-use compliance margins. Thus,

the emission benefits calculated here are likely to be understated.

The average emission factor impacts per vehicle associated with the

proposed regulations are shown in Table 4. The calculated results for

A/C control listed in Table 4 include a factor to account for driving

with the A/C ``on'' versus driving with it ``off.'' A recent survey of

actual A/C operation in Phoenix, AZ found that the compressor was

engaged about 61 percent of the time during typical ozone exceedance

days. Thus, the estimated g/mi reduction from A/C control was

multiplied by 0.61 for inclusion in Table 4.

Table 4.--Average Emission Factor Reduction Per Vehicle

------------------------------------------------------------------------

NMHC (g/ CO(g/ NOX(g/

Control area mi) mi) mi)

------------------------------------------------------------------------

High speed/accel............................. 0.055 2.39 0.062

Soak/start................................... 0.022 0.02 0.037

Air conditioning............................. 0.000 0.00 0.91

------------------------------------------------------------------------

These emission reduction numbers constitute the emission reductions

associated with the proposed requirements in g/mi. These g/mi values

were converted into the estimated lifetime emission reduction per

vehicle using assumptions about average annual mileage accumulation

rates, a discount rate of seven percent, and estimated survival rates.

The results are listed in Table 5; a detailed discussion of the

methodology can be found in the Regulatory Impact Analysis.

Table 5.--Discounted Lifetime Emission Reductions Pounds Per Vehicle

------------------------------------------------------------------------

Control area NMHC CO NOX

------------------------------------------------------------------------

US06......................................... 10.1 441 11.4

Soak/start................................... 4.1 4 6.8

Air conditioning............................. 0.0 0 16.9

--------------------------

Total.................................... 14.2 445 35.1

------------------------------------------------------------------------

The tons per summer day emission reductions in various years as a

result of the proposed test procedure modifications were estimated

using vehicle miles traveled (VMT) for different model year vehicles

during each year of interest, the emission factor reductions shown in

Table 4, and the proposed phase-in schedule. These calculations are

show in Appendix B of the Regulatory Impact Analysis (RIA) and are

summarized in Table 5. The percent reduction columns in Table 6 compare

these estimated tons per summer day (tpsd) emission reductions to the

baseline emissions for the light-duty fleet (cars and trucks).

Calculations for these percentage reductions are shown in Appendix C of

the RIA.

Table 6.--Fleet Emission Reductions in Tons/Summer Day and Percent of

Light-Duty Fleet

------------------------------------------------------------------------

NMHC CO NOX

--------------------------------------------

tpsd % tpsd % tpsd %

------------------------------------------------------------------------

2005....................... 404 4 12655 11 1000 9

2010....................... 577 6 18047 15 1427 12

2015....................... 694 7 21717 17 1717 14

2020....................... 765 8 23938 18 1892 14

------------------------------------------------------------------------

B. Economic Impact

The proposed additions to emission test procedures will impose

several costs on the original equipment manufacturers. These costs

include added hardware for improved emission control and associated

development and redesign costs, improved engine control calibrations,

and increased costs associated with the certification process including

durability data vehicle testing and reporting.

The cost estimates correspond to costs incurred by the manufacturer

in complying with the proposed requirements. These costs can be divided

into fixed and variable costs. Fixed costs are those costs made prior

to vehicle production and are relatively [[Page 7423]] independent of

production volumes. The fixed costs considered in this analysis are

those for engine control recalibration, vehicle redesign, mechanical

integrity testing on redesigned engine families, certification

durability demonstration, annual certification costs, and test facility

upgrades and construction. Variable costs are costs for the necessary

emission control hardware and are, by nature, directly dependent on

production volume. Table 7 presents a summary of the cost estimates

calculated by the Agency. Discussion of the assumptions and data

included in these estimates can be found in the RIA.

Table 7.--Regulatory Cost Estimates

------------------------------------------------------------------------

Annual cost Cost/vehicle

($ million) ($)

------------------------------------------------------------------------

US06........................................ 16.8 1.12

Soak/start.................................. 139.4-187.0 9.30-12.47

A/C......................................... 18.3 1.22

Totals.................................. 174.5-222.1 11.63-14.81

------------------------------------------------------------------------

C. Cost-Effectiveness

The cost-effectiveness estimate represents the expected cost per

ton of pollutant reduced. The costs presented in Table 7 are not

necessarily equally spread among the three pollutant emissions (NMHC,

CO, and NOX). Since the requirements associated with A/C are

targeted for NOX control, all costs associated with A/C have been

allocated to NOX. For US06, the costs associated with each area

have been allocated equally across each pollutant. As the CO reduction

from soak/start is minimal, the costs associated with soak/start have

been split equally between NMHC and NOX. Table 8 contains the per

vehicle cost allocation to each pollutant within each control area.

Table 8.--Cost Allocation ($/vehicle)

------------------------------------------------------------------------

NMHC CO NOX Total

------------------------------------------------------------------------

US06 costs....... 0.37 0.37 0.37 1.12

Soak/start costs. 4.65-6.23 0.00 4.65-6.23 9.30-12.47

A/C Costs........ 0.00 0.00 1.22 1.22

Total........ 5.02-6.61 0.37 6.24-7.83 11.63-14.81

------------------------------------------------------------------------

Dividing the costs shown in Table 8 by the lifetime emission

reductions shown in Table 5, gives the cost-effectiveness estimates

shown in Table 9.

Table 9.--Cost-Effectiveness Estimates ($/Ton)

------------------------------------------------------------------------

Control area NMHC CO NOx

------------------------------------------------------------------------

US06.................................... 74 2 65

Soak/start.............................. 2291-3072 NA 1362-1827

A/C..................................... NA NA 153

Total............................... 707-930 2 355-445

------------------------------------------------------------------------

D. Consumer Impacts

Two impacts on value to the consumer not included in the above

estimates are potential savings associated with reduced fuel

consumption and impact on the horsepower output of some vehicle

engines. As previously discussed, EPA expects manufacturers to

eliminate or greatly reduce the amount of commanded enrichment

currently used in order to meet the NMHC and CO standards for the US06

control cycle. Due to the lower fuel consumption associated with

stoichiometric air/fuel control as compared to commanded enrichment,

this action will result both in a small improvement in fuel economy and

a small loss in horsepower output. The Agency approximated the fuel

economy benefit by determining how much extra fuel is used during

commanded enrichment operating modes and the in-use incidence of these

commanded enrichment operating modes. The result was an estimated 0.51

percent reduction in fuel consumption. Using this fuel consumption

reduction and multiplying it by the miles driven in a given year, the

appropriate survival rate and a seven percent discount factor, results

in an estimated lifetime fuel economy savings of $16.56, based on a

gasoline cost of $0.80 per gallon, excluding state and federal

taxes.31 A more detailed discussion of fuel economy cost savings

can be found in the RIA for this rule.

\31\From Cost Projections, FFA, 1992, updated from DOE/EIA

Monthly Energy Review, May 1994, and DOT/FHA. According to FHA,

average sales-weighted state taxes for gasoline were 18.54 cents in

June 1994. Federal tax is 18.4 cents.

---------------------------------------------------------------------------

Accompanying the lost horsepower output will be the potential for

some consumers to consider such affected vehicles as having less value.

The Agency does not believe that this lost value will be noticed by

most consumers, as the horsepower loss is quite small, but acknowledges

its potential effect nonetheless. Due to the difficult nature of trying

to quantify a cost associated with reduced power output, or reduced 0

to 60 mph acceleration time, etc., the Agency has not been able to

quantify the loss in consumer value. However, the Agency believes that

this cost should be roughly negated by the associated savings in fuel

expenses. Comments and data are solicited on ways to quantify the

consumer value of the power loss.

The Agency does not anticipate that today's proposal will have any

impact on Inspection/Maintenance programs.

XII. Public Participation

A. Comments and the Public Docket

The Agency welcomes comments on all aspects of this proposed

rulemaking. All comments, with the exception of proprietary

information, should be directed to the EPA Air Docket Section, Docket

No. A-92-64 (see ADDRESSES). Commenters who wish to submit proprietary

information for consideration should clearly separate such information

from other comments by:

Labeling proprietary information ``Confidential Business

Information'' and

Sending proprietary information directly to the contact

person listed (see FOR FURTHER INFORMATION CONTACT) and not to the

public docket.

This will help ensure that proprietary information is not

inadvertently placed in the docket. If a commenter wants

[[Page 7424]] EPA to use a submission labeled as confidential business

information as part of the basis for the final rule, then a

nonconfidential version of the document, which summarizes the key data

or information, should be sent to the docket.

Information covered by a claim of confidentiality will be disclosed

by EPA only to the extent allowed and by the procedures set forth in 40

CFR part 2. If no claim of confidentiality accompanies the submission

when it is received by EPA, the submission may be made available to the

public without notifying the commenters.

B. Public Hearing

Anyone wishing to present testimony about this proposal at the

public hearing (see DATES) should, if possible, notify the contact

person (see FOR FURTHER INFORMATION CONTACT) at least seven days prior

to the day of the hearing. The contact person should be given an

estimate of the time required for the presentation of testimony and

notification of any need for audio/visual equipment. A sign-up sheet

will be available at the registration table the morning of the hearing

for scheduling those who have not notified the contact earlier. This

testimony will be scheduled on a first-come, first-served basis, and

will follow the testimony that is arranged in advance.

The Agency recommends that approximately 50 copies of the statement

or material to be presented be brought to the hearing for distribution

to the audience. In addition, EPA would find it helpful to receive an

advance copy of any statement or material to be presented at the

hearing at least one week before the scheduled hearing date. This is to

give EPA staff adequate time to review such material before the

hearing. Such advance copies should be submitted to the contact person

listed.

The official records of the hearing will be kept open for 30 days

following the hearing to allow submissions of rebuttal and

supplementary testimony. All such submittals should be directed to the

Air Docket, Docket No. A-92-64 (see ADDRESSES).

The hearing will be conducted informally, and technical rules of

evidence will not apply. Written transcripts of the hearing will be

made and a copy thereof placed in the docket. Anyone desiring to

purchase a copy of the transcript should make individual arrangements

with the court reporter recording the proceeding.

XIII. Administrative Designation

Under Executive Order 12866 (58 FR 51735), the Agency must

determine whether the regulatory action is ``significant'' and

therefore subject to OMB review and the requirements of the Executive

Order. The Order defines a ``significant regulatory action'' as one

that is likely to result in a rule that may:

(1) Have an annual effect on the economy of $100 million or more or

adversely affect in a material way the economy, a sector of the

economy, productivity, competition, jobs, the environment, public

health or safety, or State, local, or tribal governments or

communities;

(2) Create a serious inconsistency or otherwise interfere with an

action taken or planned by another agency;

(3) Materially alter the budgetary impact of entitlements, grants,

user fees, or loan programs or the rights and obligations of recipients

thereof; or

(4) Raise novel legal or policy issues arising out of legal

mandates, the President's priorities, or the principles set forth in

the Executive Order.

Pursuant to the terms of Executive Order 12866, it has been

determined that this rule is a ``significant regulatory action''

because of annual impacts on the economy that are likely to exceed $100

million. As such, this action was submitted to OMB for review. Changes

made in response to OMB suggestions or recommendations will be

documented in the public record.

XIV. Regulatory Flexibility Act

The Regulatory Flexibility Act of 1990 requires federal agencies to

identify potentially adverse impacts of federal regulations upon small

entities. In instances where significant impacts are possible on a

substantial number of these entities, agencies are required to perform

a Regulatory Flexibility Analysis (RFA).

The Agency has determined that this action will not have a

significant impact on a substantial number of small entities. This

regulation will affect only manufacturers of motor vehicles, a group

which does not contain a substantial number of small entities.

Therefore, as required under section 605 of the Regulatory

Flexibility Act, 5 U.S.C. 601 et. seq., I certify that this regulation

does not have a significant impact on a substantial number of small

entities.

XV. Reporting and Recordkeeping Requirement

The information collection requirements in this proposed rule have

been submitted for approval to the Office of Management and Budget

(OMB) under the Paperwork Reduction Act, 44 U.S.C. 3501 et seq. An

Information Collection Request document has been prepared by EPA (ICR

No. 2060-0104) and a copy may be obtained from Sandy Farmer,

Information Policy Branch, EPA, 401 M St., SW (Mail Code 2136),

Washington, DC 20460 or by calling (202) 260-2740.

The information collection burden associated with this rule

(testing, record keeping and reporting requirements) is estimated to

average 566 hours annually for a typical manufacturer. However, the

hours spent annually on information collection activities by a given

manufacturer depends upon manufacturer-specific variables, such as the

number of engine families, production changes, emissions defects, and

so forth. The burden estimate includes such things as reviewing

instructions, searching existing data sources, setting up and

maintaining equipment, performing emission testing, gathering and

maintaining data, performing analyses, and reviewing and submitting

information.

Send comments regarding the burden estimate or any other aspect of

this collection of information, including suggestions for reducing this

burden to Chief, Information Policy Branch, EPA, 401 M St., SW (Mail

Code 2136), Washington, DC 20460 and to the Office of Information and

Regulatory Affairs, Office of Management and Budget, Washington, DC

20503, and marked ``Attention: Desk Officer for EPA.'' The final rule

will respond to any OMB or public comments on the information

collection requirements contained in this proposal.

List of Subjects in 40 CFR Part 86

Administrative practice and procedure, Air pollution control,

Confidential business information, Environmental protection, Gasoline,

Imports, Labelling, Motor vehicles, Motor vehicle pollution, Reporting

and recordkeeping requirements.

Dated: January 31, 1995.

Carol M. Browner,

Administrator.

[FR Doc. 95-2833 Filed 2-6-95; 8:45 am]

BILLING CODE 6560-50-P