[Federal Register Volume 85, Number 92 (Tuesday, May 12, 2020)]
[Proposed Rules]
[Pages 28140-28361]
[FR Doc No: 2020-05963]

Vol. 85

Tuesday,

No. 92

May 12, 2020

Part II

Environmental Protection Agency

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

40 CFR Parts 9, 59, 60, et al.

Improvements for Heavy-Duty Engine and Vehicle Test Procedures, and
Other Technical Amendments; Proposed Rule

Federal Register / Vol. 85, No. 92 / Tuesday, May 12, 2020 / Proposed
Rules

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

ENVIRONMENTAL PROTECTION AGENCY

40 CFR Parts 9, 59, 60, 85, 86, 88, 89, 90, 91, 92, 94, 1027, 1033,
1036, 1037, 1039, 1042, 1043, 1045, 1048, 1051, 1054, 1060, 1065,
1066, and 1068

[EPA-HQ-OAR-2019-0307; FRL-10006-90-OAR]
RIN 2060-AU62

Improvements for Heavy-Duty Engine and Vehicle Test Procedures,
and Other Technical Amendments

AGENCY: Environmental Protection Agency (EPA).

ACTION: Proposed rule.

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

SUMMARY: The Environmental Protection Agency (EPA) is proposing changes
to the test procedures for heavy-duty engines and vehicles to improve
accuracy and reduce testing burden. EPA is also proposing other
regulatory amendments concerning light-duty vehicles, heavy-duty
vehicles, highway motorcycles, locomotives, marine engines, other
nonroad engines and vehicles, stationary engines. These would affect
the certification procedures for exhaust emission standards, and
related requirements. EPA is proposing similar amendments for
evaporative emission standards for nonroad equipment and portable fuel
containers. These amendments would increase compliance flexibility,
harmonize with other requirements, add clarity, correct errors, and
streamline the regulations. Given the nature of the proposed changes,
they would have neither significant environmental impacts nor
significant economic impacts for any sector.

DATES:
    Comments: Comments must be received on or before June 26, 2020.
    Public Hearing: If anyone contacts us requesting a public hearing
on or before May 19, 2020, we will hold a hearing in Ann Arbor,
Michigan at 10 a.m. on May 27, 2020.

ADDRESSES:
    Comments. Submit your comments, identified by Docket ID No. EPA-HQ-
OAR-2019-0307, at http://www.regulations.gov. Follow the online
instructions for submitting comments. Once submitted, comments cannot
be edited or removed from Regulations.gov. The EPA may publish any
comment received to its public docket. Do not submit electronically any
information you consider to be Confidential Business Information (CBI)
or other information whose disclosure is restricted by statute.
Multimedia submissions (audio, video, etc.) must be accompanied by a
written comment. The written comment is considered the official comment
and should include discussion of all points you wish to make. The EPA
will generally not consider comments or comment contents located
outside of the primary submission (i.e., on the web, cloud, or other
file sharing system). For additional submission methods, the full EPA
public comment policy, information about CBI or multimedia submissions,
and general guidance on making effective comments, please visit http://www2.epa.gov/dockets/commenting-epa-dockets.
    Public hearing. Individuals are invited to notify EPA of interest
in a public hearing; see FOR FURTHER INFORMATION CONTACT.
    Public Participation: Public hearing. If we hold a public hearing,
we will announce detailed information about the hearing on our website.
Send requests for a hearing and questions about the status of a hearing
to the contact identified in FOR FURTHER INFORMATION CONTACT.
    Comments. Submit your comments, identified by Docket ID No. EPA-HQ-
OAR-2019-0307, at http://www.regulations.gov. Follow the online
instructions for submitting comments. Once submitted, comments cannot
be edited or removed from Regulations.gov. The EPA may publish any
comment received to its public docket. Do not submit electronically any
information you consider to be Confidential Business Information (CBI)
or other information whose disclosure is restricted by statute.
Multimedia submissions (audio, video, etc.) must be accompanied by a
written comment. The written comment is considered the official comment
and should include discussion of all points you wish to make. EPA will
generally not consider comments or comment contents located outside of
the primary submission (i.e., on the web, cloud, or other file sharing
system). For additional submission methods, the full EPA public comment
policy, information about CBI or multimedia submissions, and general
guidance on making effective comments, please visit https://www.epa.gov/dockets/commenting-epa-dockets.
    Docket. EPA has established a docket for this action under Docket
ID No. EPA-HQ-OAR-2019-0307. All documents in the docket are listed on
the www.regulations.gov website. Although listed in the index, some
information is not publicly available, e.g., CBI or other information
whose disclosure is restricted by statute. Certain other material, such
as copyrighted material, is not placed on the internet and will be
publicly available only in hard copy form. Publicly available docket
materials are available either electronically in www.regulations.gov or
in hard copy at Air and Radiation Docket and Information Center, EPA
Docket Center, EPA/DC, EPA WJC West Building, 1301 Constitution Ave.
NW, Room 3334, Washington, DC. The Public Reading Room is open from
8:30 a.m. to 4:30 p.m., Monday through Friday, excluding legal
holidays. The telephone number for the Public Reading Room is (202)
566-1744, and the telephone number for the Air Docket is (202) 566-
1742.

FOR FURTHER INFORMATION CONTACT: Alan Stout, Office of Transportation
and Air Quality, Assessment and Standards Division, Environmental
Protection Agency, 2000 Traverwood Drive, Ann Arbor, MI 48105;
telephone number:<PHONE_NUMBER>; email address<EMAIL_ADDRESS>
SUPPLEMENTARY INFORMATION:

Table of Contents

I. General Information
II. Heavy-Duty Highway Amendments
    A. Test Procedures and Compliance Model Changes
    B. Heavy-Duty Engine GHG Emission Standards and Flexibility
    C. Heavy-Duty Vehicle GHG Emission Standards and Flexibility
    D. Requests for Comment on Phase 2 Regulations
    E. Other Heavy-Duty Highway Amendments
III. Other Amendments
    A. Ethanol-Blend Test Fuels for Nonroad Spark-Ignition Engines
and Vehicles, Highway Motorcycles, and Portable Fuel Containers
    B. Removing Obsolete CFR Content
    C. Certification Fees (40 CFR part 1027)
    D. Additional Amendments for Motor Vehicles and Motor Vehicle
Engines (40 CFR parts 85 and 86)
    E. Additional Amendments for Locomotives (40 CFR part 1033)
    F. Additional Amendments for Land-Based Nonroad Diesel Engines
(40 CFR part 1039)
    G. Additional Amendments for Marine Diesel Engines (40 CFR parts
1042 and 1043)
    H. Portable Fuel Containers (40 CFR part 59)
    I. Evaporative Emission Standards for Nonroad Spark-Ignition
Engines and Equipment (40 CFR part 1060)
    J. Additional Amendments for Nonroad Spark-Ignition Engines at
or Below 19 kW (40 CFR part 1054)
    K. Amendments for General Compliance Provisions (40 CFR part
1068)
    L. Other Requests for Comment
IV. Statutory Authority and Executive Order Reviews

General Information

A. Does this action apply to me?

    This action relates to companies that manufacture or sell new
gasoline fueled light-duty vehicles, light-duty trucks, medium-duty
passenger vehicles, or heavy-duty vehicles up to 14,000 pounds GVWR, as
defined under EPA's CAA regulations,\1\ and passenger automobiles
(passenger cars), non-passenger automobiles (light trucks), and heavy-
duty pickup trucks and vans as defined under National Highway Traffic
Safety Administration's (NHTSA's) Corporate Average Fuel Economy (CAFE)
regulations.\2\ Additional amendments apply for different manufacturers
of various types of nonroad and stationary engines, vehicles, and
equipment.
---------------------------------------------------------------------------

    \1\ ``Light-duty vehicle,'' ``light-duty truck,'' ``medium-duty
passenger vehicle,'' and ``heavy-duty vehicle'' are defined in 40
CFR 86.1803-01.
    \2\ ``Passenger automobile'' and ``non-passenger automobile''
are defined in 49 CFR 523.4 and 523.5, respectively. ``Heavy-duty
pickup trucks and vans'' are defined in 49 CFR 523.7.
---------------------------------------------------------------------------

    Regulated categories and entities include the following:

------------------------------------------------------------------------
                                                         Examples of
           Category               NAICS codes \A\        potentially
                                                      regulated entities
------------------------------------------------------------------------
Industry.....................  333618, 336111,       Motor vehicle
                                336112, 336120,       manufacturers and
                                336211, 336212,       engine
                                336611, 336911,       manufacturers.
                                336999.
Industry.....................  811111, 811112,       Commercial
                                811198, 423110.       importers of
                                                      vehicles and
                                                      vehicle
                                                      components.
Industry.....................  335312, 811198......  Alternative fuel
                                                      vehicle
                                                      converters.
Industry.....................  326199, 332431......  Portable fuel
                                                      container
                                                      manufacturers.
------------------------------------------------------------------------
\A\ North American Industry Classification System (NAICS).

    This list is not intended to be exhaustive, but rather provides a
guide for readers regarding entities likely to be regulated by this
action. If you have questions regarding the applicability of this
action to a particular entity, consult the person listed in the FOR
FURTHER INFORMATION CONTACT section.

B. What action is the Agency taking?

    This action proposes to amend the regulations that implement our
air pollutant emission standards for engines, vehicles and mobile
equipment. The proposed amendments, which are generally technical
amendments that include corrections, clarifications, and flexibilities.
In other words, this proposal comprises a significant variety of small
changes for multiple types of engines and equipment.
    The majority of amendments being proposed would modify existing
test procedures for heavy-duty highway engines and vehicles. These test
procedure changes would improve accuracy, and in some cases, reduce
test burden. They would apply for measurement of criteria pollutants
(such as NOX), as well as greenhouse gas pollutants
(primarily CO2).
    Other heavy-duty highway amendments would update EPA regulations to
enhance implementation of existing emission standards. For example,
some changes would reduce the likelihood that manufacturers would need
to duplicate certification efforts to comply with EPA, Canadian, and
Californian standards. Some amendments would make it easier for
manufacturers to more fully account for the emission benefits of
advanced emission control technology, which could provide them the
opportunity to generate additional emission credits. These heavy-duty
highway amendments are described in Section II.
    This notice also proposes other amendments that are generally
administrative or technical in nature and include amendments for
nonroad engines and vehicles. These amendments are described in Section
III. Perhaps the most visible administrative amendment would be the
elimination of hundreds of pages of obsolete regulations, which is
described in Section III.B.

C. What are the incremental costs and benefits of this action?

    This action is limited in scope and is not intended to include
amendments that would have significant economic or environmental
impacts. EPA has not drafted a Regulatory Impact Analysis.

Heavy-Duty Highway Amendments

A. Test Procedures and Compliance Model Changes

    Since the promulgation of the Phase 2 regulations, manufacturers
have been revising their internal test procedures to ensure they will
be able to comply with the new requirements that begin in model year
2021. In doing so, they have identified several areas in which the test
procedure regulations could be improved (in terms of overall accuracy,
repeatability and clarity) without changing the effective stringency of
the standards. Commenters who believe that EPA has included changes
that change the stringency of the standards are encouraged to consider
the potential impact in the context of the full range of proposed
changes to the test procedures, and to suggest ways in which EPA could
avoid the impact of such changes on stringency.
    EPA is proposing numerous changes to the test procedure regulations
to address manufacturers' concerns and to address other issues we have
identified. These proposed changes are described below. The list
includes numerous editorial changes that simply correct typographical/
formatting errors or revise the text to improve clarity. Although these
amendments are being proposed primarily in the context of heavy-duty
engines and vehicles, the proposed amendments to part 1065 will also
apply to nonroad engines, and the proposed amendments to part 1066 will
also apply to light-duty vehicles. However, since these amendments are
mostly editorial or adding flexibility, they will not adversely impact
these other sectors.
1. 40 CFR Part 1036 Test Procedures
    The regulations in 40 CFR part 1036, subpart F, specify how to
measure emissions from heavy-duty engines. The test procedure
amendments being proposed for part 1036 are primarily for the purposes
of adding flexibility and reducing variability in test results.
Additional information that led to proposal of many of these changes
arose from a test program at Southwest Research Institute (SwRI) that
was jointly funded by EPA and the Engine Manufacturers Association
(EMA). These amendments are summarized below, and readers are referred
to the proposed part 1036, subpart F regulatory text for additional
information. Amendments for other subparts of part 1036 (i.e.,
amendments not directly related to test procedures) are discussed in
Section I.C.
     1036.501(g)--Adding a new paragraph (g) to denote duty
cycles for testing MY 2016-2020 engines.

     1036.501(h)--Adding a new paragraph (h)(2) to cross-
reference citation of transient test cycle specification for testing MY
2021 and later engines. In paragraph (h)(3)(ii), adding clarification
that weighting factors for the Ramped Modal Cycle (RMC) are to be
applied to CO2 to calculate the composite emission result.
Note that this proposed rule includes amendments to refer to the
steady-state duty cycle as the Ramped Modal Cycle rather than the
Supplemental Emission Test.
     1036.503--Migrating 1036.510 to new 1036.503. Updating
existing paragraph (c) and adding a new (c)(4) and (d)(4). The new text
specifies that the engine manufacturer must provide idle speed and
torque to the vehicle manufacturer. Additional direction given on
handling data points for a low speed governor where the governor is
active.
     1036.505--Adding a new paragraph (b) to give direction on
both engine and powertrain testing. Modifying Table 1 to include
vehicle speed and grade parameters to facilitate the hybrid powertrain
testing option.
     1036.510--Adding a new section regarding transient testing
of engines and hybrids to facilitate hybrid certification for both GHG
and criteria pollutants.
     1036.525(d)(4)(ii)--Editorial revisions to equation and
example calculations.
     1036.527--New section added to provide a means to
determine hybrid powertrain systems rated power. This is needed to
facilitate the addition of the hybrid powertrain testing option.
     1036.530(b)(1)(i) and (2)--Updating to require test fuel
mass-specific energy content to be analyzed by three different labs and
the arithmetic mean to be used in the calculation. Updating carbon mass
fraction determination to allow analysis by a single lab only to
facilitate on-line analysis from pipeline supplied natural gas. Updated
to add ASTM method for determination of test fuel mass-specific energy
content for natural gas.
     1036.530 Table 1--Updated footnote format in table.
     1036.535--Generally updating to improve the engine fuel
mapping test procedures based on the jointly funded EPA-EMA test
program. The overall result of these updates is to reduce the
variability of the emission test results to improve lab-to-lab
variability.
     1036.540--Generally updating to improve the cycle-average
fuel mapping test procedure as a result of the jointly funded EPA-EMA
test program at SwRI. The overall result of these updates is to reduce
the variability of the emission test results to improve lab-to-lab
variability.
     1036.543--Adding new section to address carbon balance
error verification. This is a result of the jointly funded EPA-EMA test
program. The overall result of these updates is to reduce the
variability of the emission test results to improve lab-to-lab
variability.
2. 40 CFR Part 1037 Test Procedures
    The regulations in 40 CFR part 1037, subpart F, specify how to
measure emissions from heavy-duty vehicles. They also specify how to
measure certain GEM inputs, such as aerodynamic drag, rolling
resistance, and axle efficiency. The test procedure amendments being
proposed for part 1037, which are summarized below, are primarily for
the purpose of reducing variability in test results and adding optional
test procedures. Given the technical nature of these proposed
amendments, readers are referred to the regulatory text for additional
details. Proposed amendments for other subparts of part 1037 (i.e.,
amendments not directly related to test procedures) are discussed in
Section I.C.
     1037.105 Table 1--Updated footnote format in table.
     1037.106 Table 1--Updated footnote format in table.
     1037.510(a)(2) and (e)--Edit in (a)(2) introductory
paragraph. Updating (a)(2)(ii) and (iii) as result of the jointly
funded EPA-Engine Manufacturers Association (EMA) test program at SwRI.
The overall result of these updates is to reduce the variability of the
emission test results to improve lab-to-lab variability. Update (e)
making use of cruise control optional as variability can be high if
cruise control is used.
     1037.510 Table 1--Updated footnote format in table.
     1037.515 Table 3--Updated footnote format in table.
     1037.520 Table 1 and (f)--Correcting typo in CdA value for
low-roof cabs for Bin III. Updating cross-reference in (f).
     1037.520(g)--Adding some additional vehicle
characteristics that need to be reported. Also providing clarification
on the application of the 6x4D drive axle configuration. This includes
a better description of the application as well as qualifiers that
allow for use of this configuration.
     1037.520(i)--Adding torque converter characterization.
     1037.520 Table 1--Updating Table to include additional
technologies and GEM input values for automatic engine shutdown
systems.
     1037.520(j)(5)--Correcting error that transposed school
and coach bus GEM inputs.
     1037.520 Table 6--Updated footnote format in table.
     1037.528(h)(6)(ii)--Adding direction to use good
engineering judgment when measuring rolling resistance for equation 11.
     1037.528--Updating equation 14. The ``+'' is replaced with
a ``-'', correcting a typo.
     1037.534--Updating equation 6, and corresponding example
problem. The update applies italics to ``i''.
     1037.540--Updating equations 1, 2, and 3. The update
applies italics to ``i''.
     1037.540(e) and (f)--Adding section reference for location
of standard payload.
     1037.540 Table 1--Updated footnote format in table.
     1037.550--Global updates as a result of the joint EPA-EMA
fuel mapping test program at SwRI and general improvements based on
experience gained from testing powertrain systems. The overall result
of these updates is to reduce the variability of the emission test
results to improve lab-to-lab variability.
     1037.551--Updating reference.
     1037.555--Updating equations 1 and 3, edits. The updates
apply italics to ``i''.
     1037.560--Making it optional to drain gear oil after break
in. Providing the option of an alternative temperature range to provide
harmonization with EC test procedure. Also, edits pertaining to improve
the readability of the Ploss (i.e., power loss) variable description.
     1037.565--Providing an option to map additional test
points. Also, edits pertaining to improve the readability of the Ploss
variable description.
     1037.570--Adding new section to determine torque converter
capacity factor. This will allow a manufacturer to determine their own
torque converter capacity factor instead of using the default value
provided in GEM. The option to use the default value still remains.
3. 40 CFR Part 1065 Test Procedures
    The regulations in 40 CFR part 1065 specify general procedures for
measuring emissions from engines--heavy-duty highway engines, as well
as nonroad engines. The amendments being proposed for part 1065, which
are summarized below, are primarily for the purpose of reducing
variability in test results.
    The regulations in part 1065 rely heavily on acronyms and
abbreviations (see 40 CFR 1065.1005 for a complete list). Acronyms used
here are summarized in the following table:

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

------------------------------------------------------------------------
ASTM.............................  American Society for Testing and
                                    Materials
CVS..............................  Constant-Volume Sampler
DEF..............................  Diesel Exhaust Fluid
ECM..............................  Electronic Control Module
NIST.............................  National Institute for Standards and
                                    Technology
NMC FID..........................  Nonmethane Cutter with a Flame
                                    Ionization Detector
NMHC.............................  Nonmethane Hydrocarbon
NMNEHC...........................  Nonmethane Nonethane Hydrocarbon
RMC..............................  Ramped Modal Cycle
THC FID..........................  Flame Ionization Detector for Total
                                    Hydrocarbons
------------------------------------------------------------------------

    In addition to the amendments listed below that are being proposed
for part 1065, we request comment on the use of ASTM test method D2784
to measure the sulfur content in liquefied petroleum gas test fuels.
This method, which is specified as the applicable test method in Sec.
1065.720, has been withdrawn by ASTM without replacement. We request
comment on whether we should continue to specify this method or specify
an active method. For example, should we specify ASTM D6667 instead and
incorporate it by reference into the regulations?
     1065.1(g)--Updated test procedure URL.
     1065.130(e)--Revised language to denote that carbon
balance should be performed to verify exhaust system integrity in place
of chemical balance.
     1065.140(c)(6)(i)--Corrected typo. Replaced ``dew point''
with ``dewpoint''.
     1065.140(e)(2)--Revised language to add clarification on
how to determine minimum dilution ratio for discrete mode testing.
     1065.145(e)(3)(i)--Removed requirement to heat sample pump
if it is located upstream of a NOX converter or chiller.
Replaced with requirement to design the sample system to prevent
aqueous condensation. Given that the concern is loss of NO2
in the sampling system, the pump itself doesn't necessarily need to be
heated as there are a number of ways to prevent condensation.
     1065.170--Revised to allow you to stop sampling during
hybrid tests when the engine is off and allow exclusion of the sampling
off portions of the test from the proportional sampling verification.
Also added provision for hybrid testing to allow supplemental dilution
air to be added to the bag in the event that sampled volumes are too
low for emission analysis.
     1065.205 Table 1--Revised with edits and the addition of a
recommended performance specification for fuel mass scales to reduced
fuel flow measurement error.
     1065.220(a) introductory and (a)(3)--Updated the
application of fuel flow meter to more correctly reflect how and what
they are used for in 1065.
     1065.225(a) introductory and (a)(3)--Updated the
application of intake flow meter to more correctly reflect how and what
they are used for in 1065.
     1065.247(c)(2)--Edit to apply requirements to DEF dosing
unit rather than to the engine.
     1065.260(e)--Add the word ``some'' as a qualifier for
gaseous fueled engines with respect to using the additive method for
NMHC determination.
     1065.266--Updated URL.
     1065.275--Deleted URL and replaced with reference to URL
in 1065.266.
     1065.280(a)--Updated to reflect that there is no method in
1065.650 for determining oxygen balance and that you should develop a
method using good engineering judgment.
     1065.303 Table 1--Updated for formatting. Updated to add
Fuel mass scale and DEF mass scale to the linearity verifications in
1065.307. Updated verification in 1065.341 to replace ``batch sampler''
with ``PFD'' as PFD is the preferred language. Updated one, and added
two, footnotes excluding linearity verification for DEF flow if the ECM
is used and for fuel and intake air flow if propane checks or carbon
balance is performed. This is not a new exemption, it just relocates it
to the footnote area.
     1065.307(d)(4)--Revised to include DEF mass flow rate. The
paragraph is also enhanced to include additional requirement to correct
or account for buoyancy effects and flow disturbances to improve the
flow measurement.
     1065.307(d)(6)(i)--Revised to state that the span gas can
only contain one single constituent in balance air (or N2 if
using a gas analyzer) as the reference signal for linearity
determination.
     1065.307(d)(7)--Revised to state that the span gas can
only contain one single constituent in balance air (or N2 if
using a gas analyzer) as the reference signal for linearity
determination.
     1065.307(d)(9)--Expanded paragraph to include fuel and DEF
mass scales and provided additional requirements for performing the
linearity verification on these scales.
     1065.370(e)(3)(i) and (ii)--Edits to make intent clear.
     1065.307(e)(3)(iii)--Defined mmax for a fuel
mass scale.
     1065.307(e)(5)--Provided additional information
surrounding requirements for using a propane check or carbon balance
verification in place of a flow meter linearity verification.
     1065.307(e)(7)(i)(F) and (G)--Added transmission oil and
axle gear oil to temperature measurements that require linearity
verification.
     1065.307 Table 1--Added DEF flow rate.
     1065.307 Table 2--Added a new Table 2 to provided
additional guidance on when optional verifications to the flow meter
linearity verifications can be used.
     1065.309(d)(2)--Updated to allow the use of water vapor
injection for humidification of gases.
     1065.315(a)(3)--Editorial revisions.
     1065.320(b) and (c)--Deleted the existing paragraph (b)
and moved the existing (c) to (b) as this is now adequately covered in
1065.307.
     1065.341 introductory text--Revised to clarify which
subparagraphs apply to CVS and which apply to PFD.
     1065.341(g)--Revised to replace ``batch sampler'' with
``PFD'' throughout. Also, edited to provide further clarification on
the procedure.
     1065.341(h)--New paragraph added to reference Table 2 of
1065.307 regarding when alternate verifications can be used.
     1065.342(d)(2)--Updated to allow the use of water vapor
injection for humidification of gases.
     1065.350(d)(2)--Updated to allow the use of water vapor
injection for humidification of gases.
     1065.355(d)(2)--Updated to allow the use of water vapor
injection for humidification of gases.
     1065.360(a)(4)--Added new requirement to determine methane
and ethane THC FID response factors as a function of exhaust molar
water content when measuring emissions from a gaseous fueled engine.
This is to account for the effect water has on non-methane cutters.
     1065.360(d)(12)--Added process to determine methane and
ethane THC FID response factors as a function of exhaust molar water
content when measuring emissions from a gaseous fueled engine. This is
to account for the effect water has on non-methane cutters.
     1065.365(d)--Added new requirement to determine NMC FID
methane penetration fraction and ethane response factor as a function
of exhaust molar water content when measuring emissions from a gaseous
fueled engine. This is to account for the effect water has on non-
methane cutters.
     1065.365(d)(10) and (11)--Added process to determine NMC
FID methane penetration fraction and ethane response factors as a
function of exhaust molar water content when measuring emissions from a
gaseous fueled engine. This is to account for the effect water has on
non-methane cutters.

     1065.370(e)(5)--Updated to allow the use of water vapor
injection for humidification of gases.
     1065.375(d)(2)--Updated to allow the use of water vapor
injection for humidification of gases.
     1065.410(d)--Updated to state that you may repair a test
engine if the parts are unrelated to emissions without prior approval.
If the part may affect emissions, prior approval is required.
     1065.510(a), (b)(5)(i), and (f)(4)(i)--Removed requirement
for engine stabilization during mapping and relocated it to
1065.510(b)(5)(i), which lays out the mapping procedure. Added a
recommended stabilization time at each setpoint. Also added allowance
to specify CITT as a function of idle speed in cases where an engine
has an adjustable warm idle or enhanced idle.
     1065.512(b)(1) and (2)--Added additional procedures on how
to operate the engine and validate the duty-cycle when an engine
utilized enhanced-idle speed. This also addresses denormalization of
the reference torque when enhanced-idle speed is active.
     1065.530(a)(2)(iii)--Added new instruction on how to
determine that the engine temperature has stabilized for air cooled
engines. Part 1065 is deficient on how to determine this.
     1065.530(g)(5)--New paragraph to cover carbon balance
error verification if it is performed as part of the test sequence.
     1065.543--New section on carbon balance error verification
procedure. This was added to further reduce measurement variability for
the fuel mapping test procedure in part 1036.
     1065.602(b), (c), (d), (e), (g), (h), (j), (k)--Editorial
revisions. The updates apply italics to ``i''.
     1065.602 Table 2--Corrected an Nref-1 typo for value
``22''. It was mistakenly listed as ``20''.
     1065.602(f)--Updated footnote format in table.
     1065.610(a)(1)(iv)--Editorial updates applying italics to
``i''.
     1065.610(a)(2)--Clarification to denote that the alternate
maximum test speed determined is for all duty-cycles.
     1065.610(d)(3)--Added provision to use good engineering
judgment to come up with an alternate procedure for adjusting CITT as a
function of speed.
     1065.640(a) and (d)(1)--Deleting a comma in (a)(1).
Providing a conversion to kg/mol for Mmix in (d)(1). Also correcting an
error in the example problem to equation 1065.640-10 where Mmix was
used with the wrong units.
     1065.642(b)--Section reference correction.
     1065.642(c)(1)--Defining Cf.
     1065.643--New section on carbon balance error verification
calculations to support the new section 1065.543.
     1065.650(b)(3)--Added DEF to what is needed for chemical
balance.
     1065.650(c)(1)--Relocated transformation time requirement
here from 1065.650(c)(2)(i).
     1065.650(c)(3)--Equation edit. The update applies italics
to ``i''.
     1065.650(d)(7)--Editorial updates applying italics to
``i''.
     1065.650(f)(2)--Added DEF to what is needed for chemical
balance.
     1065.655 title--Added ``DEF''.
     1065.655(c)(3)--Updated xccombdry variable
description to include injected fluid.
     1065.655(e)(1)(i)--Added additional clarity regarding
determination of carbon and hydrogen mass fraction of fuel,
specifically to S and N content.
     1065.655(e)(4)--Equation and variable edits for format.
The updates apply italics to ``i''.
     1065.655 Table 1--Updated reference.
     1065.655(f)(3)--Restricted the use of equation 1065.655-25
if the standard setting part requires carbon balance verification.
Also, the section contains edits for format.
     1065.655(g)(1)--Updated reference.
     1065.659(c)(2) and (3)--Added DEF to chemical balance.
     1065.660(b)(4)--Variable edit. Corrected chemical formula
typo for acetaldehyde.
     1065.660(c)(2)--Included NMC FID as allowable option in
NMNEHC calculation.
     1065.665(a)--Deleted the variable and description for
C# as it is not used in any calculation in this section.
     1065.667(d)--Added DEF to chemical balance description.
     1065.695(c)(8)(v)--Added carbon balance verification.
     1065.701(b)--Updated title for California gasoline type.
     1065.701 Table 1--Updated footnote format in table.
     1065.703 Table 1--Updated to correct units for kinematic
viscosity and updated footnote format in table.
     1065.705 Table 1--Updated to correct units for kinematic
viscosity and updated footnote format in table.
     1065.710 Table 1--Edits for format consistency and updated
footnote format in table.
     1065.710 Table 2--Edits for format consistency. Added
allowance to use ASTM D5769 for total aromatic content determination
and ASTM D6550 for olefin determination. These were added because the
dye used in the current method, ASTM D1319 is becoming scarce and thus
an alternate method is needed. Updated footnote format in table.
     1065.715 Table 1--Updated footnote format in table.
     1065.720 Table 1--Updated footnote format in table.
     1065.750 Table 1--Updated footnote format in table.
     1065.905 Table 1--Updated footnote format in table.
     1065.915 Table 1--Updated footnote format in table.
     1065.1001--Updated definition of test interval to note
that the mass of emissions is determined over it.
     1065.1005(a)--Updated footnote format in table.
     1065.1005(a), (c) and (d)--Updated to follow NIST SP-811
format.
     1065.1005(a) and (e)--symbols and subscripts updated to
reflect new one added during the above revisions to part 1065.
     1065.1005(f)(2)--molar mass of ethane added. Updated
footnote format in table.
4. 40 CFR Part 1066 Test Procedures
    The regulations in 40 CFR part 1066, specify general procedures for
measuring emissions from vehicles. The amendments being proposed for
part 1066, which are summarized below, are primarily editorial.
     1066.1(g)--Updated to current URL.
     1066.135(a)(1)--Widened the range for verifications of a
gas divider derived analyzer calibration curve to 10 to 60%. This is to
ease lab burden with respect to the number of gas cylinders they must
have on hand. Also, made this midspan check optional as it is no longer
needed because part 1066 requires yearly linearity verification of the
gas divider.
     1066.210(d)(3)--Changed acceleration of Earth's gravity
from calculation under 40 CFR 1065.630 to a default value of 9.80665 m/
s\2\. This was changed because the track coastdown doesn't take place
in the same location that the dynamometer resides. Therefore, best
practice is to use a default value for gravity.
     1066.255(c)--Added clarification that the torque
transducer zero and span are mathematically done prior to the start of
the procedure.
     1066.270(c)(4)--Corrected units for force in mean force
variable description. Corrected example problem solution.
     1066.275--Extended the frequency to an optional 7 days
prior to testing if historic data from the test site supports a
frequency of more than 1 day.
     1066.405--Updated title to include ``maintenance''.
     1066.405(a)-(c)--Moved introductory paragraph to (a).
Created

new paragraphs (b) and (c) to address test vehicle inspection,
maintenance and repair, consistent with 1065.410.
     1066.420 Table 1--Updated footnote format in table.
     1066.605--Edit in paragraph (c)(4), NMHC typo, corrected
to NMHCE. Edits to equation 1066.605-10, italics added for format
consistency.
     1066.610--Edit to equation 1066.610-4. Italics added for
format consistency.
     1066.710(c)(1)(A)--Updated for clarity.
     1066.710(c)(2)--Updated to more clearly reflect how
automatic HVAC control operates in vehicles and how it should be
operated for the test.
     1066.801 Figure 1--Updated to reflect that the initial
vehicle soak, as outlined in the regulations, is a 6-hour minimum and
not a range of 6 to 36 hours.
     1066.930--Added a period to the end of the sentence.
     1066.1005(c) and (d)--Updated to follow NIST SP-811
format.
     1066.1005(f)--Updated footnote format in table.
5. Greenhouse Gas Emissions Model (GEM)
    GEM is a computer application that estimates the greenhouse gas
(GHG) emissions and fuel efficiency performance of specific aspects of
heavy-duty (HD) vehicles. Under the existing Phase 2 regulations, GEM
3.0 is used to determine compliance with the Phase 2 standards from
several vehicle-specific inputs, such as engine fuel maps, aerodynamic
drag coefficients, and vehicle weight rating.\3\ GEM simulates engine
operation over two cruise cycles, one transient cycle, and for
vocational vehicles, idle operation. These results are weighted by GEM
to provide a composite GEM score that is compared to the standard.
---------------------------------------------------------------------------

    \3\ Greenhouse gas Emissions Model (GEM) Phase 2, Version 3.0,
July 2016. A working version of this software is also available for
download at http://www.epa.gov/otaq/climate/gem.htm. This version
has been incorporated by reference at 40 CFR 1037.810.
---------------------------------------------------------------------------

    EPA is to incorporate by reference into the regulations a revised
version of GEM (Version 3.5) for manufacturers to demonstrate
compliance with the Phase 2 standards.\4\ The following changes have
been incorporated in the proposed new version, to allow additional
compliance flexibilities and improve the vehicle simulation:
---------------------------------------------------------------------------

    \4\ Greenhouse gas Emissions Model (GEM) Phase 2, Version 3.5,
November 2019. A working version of this software is also available
for download at http://www.epa.gov/otaq/climate/gem.htm.
---------------------------------------------------------------------------

     Correcting how idle emission rates are used in the model.
     Increasing the allowable weight reduction range to 25,000
pounds.
     For powertrain input, adding an input for powertrain rated
power to scale default engine power.
     Recalibrated driver over speed allowance on cruise cycles
from 3 mph to 2.5 mph.
     Revised engine cycle generation outputs with corrected
engine cycle generation torque output from model based on simulated
inertia and rate limited speed target.
     Added scaling of powertrain simulation default engine and
transmission maps based on new rated power input.
     Changed interpolation of fuel map used in post processing
to be consistent with one used in simulation.
     Powertrain accessory load correction.
     Add torque converter k-factor input option.
     Cycle average cycles: add flag for points that are to be
considered ``idle.''
     Improved handling of large input tables.
    Of these, the changes for idling emissions are the most
significant. GEM 3.0 included an error where parked idle fuel map was
used for ARB transient idle correction, which has been corrected for
GEM 3.5 to use the drive idle portion of the map. (Note also that
parked fuel map is now only required for vocational vehicles.) GEM 3.5
reads idle speed from the vehicle file and allows manufacturers to use
default values that EPA used to develop the standards. Other idle
changes include additional adjustments to cycle average fuel for
differences between mapped idle and simulated idle using non-moving
average speed and load of the ARB transient cycle average map,
regression lookup of cycle average map uses only portions with vehicle
moving, and post-process adjustment to fuel consumption based on
simulated idle speed/load.
    Preliminary evaluations of GEM 3.5 indicate that there is little
difference between GEM 3.0 and GEM 3.5 for cruise cycle operation.
However, it is possible some minor differences may be observed for
transient and idle operation of some vocational vehicles. We request
comment on whether these differences would impact impact the effective
stringency of the standards and whether either GEM or the regulations
need to be revised to address them.

B. Heavy-Duty Engine GHG Emission Standards and Flexibility

1. Vocational Engines and Emission Credits
    We are proposing to revise how Phase 1 engine credits from
vocational engines are treated in the Phase 2 program. As described
below, we are proposing to allow more flexibility provided the credits
are adjusted to accurately reflect the correct baseline.
    In developing the baseline emission rates for vocational engines in
the final Phase 2 rulemaking, we considered MY 2016 FTP certification
data for diesel engines, which showed an unexpected step-change
improvement in engine fuel consumption and CO2 emissions
compared to data considered in the proposed rule. The proposed baseline
emission rates came from the Phase 1 standards, which in turn were
derived from our estimates of emission rates for 2010 engines. The
underlying reasons for this shift in the final rule were mostly related
to manufacturers optimizing their SCR thermal management strategy over
the FTP in ways that we (mistakenly) thought they already had in MY
2010 (i.e., the Phase 1 baseline).
    As background, the FTP includes a cold-start, a hot-start and
significant time spent at engine idle. During these portions of the
FTP, the NOX SCR system can cool down and lose
NOX reducing efficiency. To maintain SCR temperature,
manufacturers initially used a simplistic strategy of burning extra
fuel to heat the exhaust system. However, during the development of
Phase 1, EPA believed manufacturers were using more sophisticated and
efficient strategies to maintain SCR temperature. EPA's
misunderstanding of the baseline technology for Phase 1 provided engine
manufacturers the opportunity to generate windfall credits against the
FTP standards.
    For the Phase 2 FRM, EPA revised the baseline emission rate for
vocational engines to reflect the actual certified emission levels. The
Phase 2 vocational engine final CO2 baseline emissions are
shown in the table below. More detailed analyses on these Phase 2
baseline values of tractor and vocational vehicles can be found in
Chapter 2.7.4 of the Phase 2 Final RIA.\5\
---------------------------------------------------------------------------

    \5\ Greenhouse Gas Emissions and Fuel Efficiency Standards for
Medium- and Heavy-Duty Engines and Vehicles--Phase 2. Regulatory
Impact Analysis, August 2016, EPA-420-R-16-900. See p. 2-76.

  Phase 2 Vocational Engine CO2 and Fuel Consumption Baseline Emissions
------------------------------------------------------------------------
                    Units                        HHD      MHD      LHD
------------------------------------------------------------------------
g/bhp-hr.....................................      525      558      576
gal/100 bhp-hr...............................   5.1572   5.4813   5.6582
------------------------------------------------------------------------

    EPA did not allow the carryover of Phase 1 vocational engine
credits into the Phase 2 program, consistent with these adjustments to
the baselines. Since this issue does not apply for RMC emissions, the
restriction was applied only for engines certified exclusively to the
FTP standards (rather than both FTP and RMC standards). We believed
that allowing engine credits generated against the Phase 1 diesel FTP
standards to be carried over into the Phase 2 program would have
inappropriately diluted the Phase 2 engine program. However, this was
in the context of unadjusted credits. After further consideration, we
now believe that it would not dilute the program if the credits were
appropriately adjusted to more accurately reflect improvement over the
true baseline levels.
    Allowing the portion of the credits that represent actual emission
improvements to be carried forward would be consistent with our
rationale from Phase 2. Thus, we are proposing in Sec.  1036.701(j)
that for Phase 1 vocational engines with emissions below the Phase 2
baseline engine values, manufacturers may recalculate and generate
credits relative to the baseline levels. The recalculated vocational
engine credits would be allowed into the Phase 2 engine program to the
same extent as tractor engine credits.
    As noted in the Phase 2 FRM, allowing additional flexibility for
compliance with engine standards does not cause any increase in
emissions because the manufacturers must still comply with the vehicle
standards. (See 81 FR 73499). However, this flexibility could allow
some manufacturers to find a less expensive compliance path. We request
comment on these proposed changes and any potential impact.
2. Confirmatory Testing of Engines and Measurement Variability
    During the Phase 2 rulemaking, manufacturers raised concern about
measurement variability impacting the stringency of the engine GHG
standards and fuel map requirements. As noted in the Phase 2 FRM, the
final standards were developed to account for this. (81 FR 73571,
October 25, 2016).
    Manufacturers raised particular concern about variability of fuel
map measurements because neither they nor EPA had sufficient experience
measuring fuel maps (in a regulatory context) to fully understand
potential impacts. We estimated the fuel map uncertainty to be
equivalent to the uncertainty associated with measuring CO2
emission and fuel consumption over the FTP and RMC cycles, which we
estimated to be about one percent. However, the Phase 2 FRM further
noted that we would incorporate test procedure improvements that would
futher reduce test result uncertainty. We also noted that: ``If we
determine in the future . . . that the +1.0 percent we factored into
our stringency analysis was inappropriately low or high, we will
promulgate technical amendments to the regulations to address any
inappropriate impact this +1.0 percent had on the stringency of the
engine and vehicle standards.'' (81 FR 73571, October 25, 2016)
    In conjunction with this commitment, EPA agreed to work with engine
manufacturers to better understand the variability of measuring fuel
maps. Through that work, we identified several sources of variability
that could be reduced by making small changes to the test procedures.
EPA is proposing these changes, which are listed in Sections I.A.1
through I.A.3 of this NPRM.
    SwRI performed emission measurements in multiple test cells and
identified distributions of error for other test inputs such measured
fuel properties and calibration gas concentrations. SwRI then used a
Monte Carlo simulation to estimate a distribution of errors in measured
fuel maps.\6\ After reviewing the results, EPA has three significant
observations:
---------------------------------------------------------------------------

    \6\ ``Measurement Variability Assessment of the GHG Phase 2 Fuel
Mapping Procedure'', Southwest Research Institute, Final Report,
December 2019.
---------------------------------------------------------------------------

    1. The variability of measuring CO2 and fuel consumption
during fuel mapping is greater than the one percent assumed in the
Phase 2 FRM.
    2. The variability of measuring CO2 and fuel consumption
during the fuel mapping procedure is roughly the same as that of the
FTP and RMC cycles.
    3. Measuring CO2 and fuel consumption at idle is
particularly challenging.
    Given these results, we understand why manufacturers would be
concerned about the possibility of EPA changing an official fuel map
results as a consequence of EPA confirmatory testing where the measured
maps were within the expected range of variability. On the other hand,
the similarity between the variability of measuring fuel maps and the
variability of measuring CO2 and fuel consumption over the
FTP and RMC cycles (measurements for which EPA has already determined
in both Phase 1 and Phase 2 that no such allowances are needed)
suggests that manufacturers should ultimately be able to comply without
any special provisions.
    We are also considering this issue in the context of our
longstanding policy that emission measurements made at our National
Vehicle and Fuel Emissions Laboratory are official emission results.
(See for example, Sec.  1036.235.) We are hesitant to change any long-
standing policy in a technical amendment rulemaking. Nevertheless,
while we believe this issue ultimately will need to be addressed in a
broader context, we are proposing a transitional approach to address
the issue of engine mapping variability, as discussed below.
    We are proposing an interim provision in 40 CFR 1036.150, under
which EPA will not replace a manufacturer's fuel maps during
confirmatory testing if the EPA-measured fuel maps were within 2.0
percent of the manufacturer's maps. We are proposing this as an interim
provision but are not including an end date at this time. We would
intend to reevaluate this provision as we learn more about the impact
of measurement variability during fuel mapping, including the full
impact of the proposed test procedure improvements that are intended to
reduce measurement variability.
    Since, this 2.0 percent reflects real testing variability, EPA
anticipates that manufacturers could not know how the variability would
affect an individual test result, which would preclude them from
relying upon this margin for compliance in current engine designs or in
any potential engine redesign. Additionally, EPA emphasizes that we are
proposing to adopt this as an interim provision, and thus manufacturers
should not otherwise rely on this provision as a compliance strategy
for engine design, as EPA intends to revisit it based on further data
and developments.
    We are also proposing an algorithm for comparing fuel maps to one
another. Because fuel maps are multi-point surfaces instead of single
values, it would be a common occurrence that some of EPA's points would
be higher than the manufacturer's while others would be lower.
    We propose that EPA's measured fuel maps would be used with GEM
according to Sec.  1036.540 to generate emission duty cycles which
simulate several different vehicle configurations, generating emission
results for each of the vehicles for each of the duty cycles.

Each individual duty cycle result could be weighted using the
appropriate vehicle category weighting factors in Table 1 of 40 CFR
1037.510 to determine a composite CO2 emission value for
that vehicle configuration. If the process is repeated for the
manufacturer's fuel maps, the average percent difference between fuel
maps could be calculated as:
[GRAPHIC] [TIFF OMITTED] TP12MY20.000

Where:

i = an indexing variable that represents one individual weighted
duty cycle result for a vehicle configuration.
N = total number of vehicle configurations.
eCO2compEPA = total composite mass of CO2 emissions in g/
ton-mile for the EPA confirmatory test, rounded to the nearest whole
number for vocational vehicles and to the first decimal place for
tractors.
eCO2compManu = total composite mass of CO2 emissions in
g/ton-mile for the manufacturer test, rounded to the nearest whole
number for vocational vehicles and to the first decimal place for
tractors.

    We request comment on the interim approach, and whether it
appropriately balances the impacts of testing variability for fuel
maps.
3. Other Minor Heavy-Duty Engine Amendments
    EPA is proposing three additional amendments to part 1036:
     Correcting the assigned N2O deterioration
factor in Sec.  1036.150(g). In the Phase 2 NPRM, EPA proposed to lower
the N2O standard from 0.10 g/hp-hr to 0.05 g/hp-hr for model
year 2021 and later diesel engines. In that context, we also proposed
to lower the assigned deterioration factor (DF) from 0.020 g/hp-hr to
0.010 g/hp-hr for model year 2021 and later diesel engines. EPA
explained in the preamble that we were not finalizing the change to the
standard (81 FR 73530), but inadvertently finalized the proposed DF
change in the regulations. Today, EPA is proposing to correct the DF
back to 0.020 g/hp-hr for all diesel engines, consistent with the
continuation of the 0.10 g/hp-hr N2O standard.
     Clarifying a reference to non-gasoline engine families in
Sec.  1036.705(b)(5). The second sentence of Sec.  1036.705(b)(5) is
intended to refer to non-gasoline engine families. However, the
existing text is not clear. As written, it can be read to mean that
gasoline engine families may not generate emission credits. EPA is
proposing to add ``non-gasoline'' to make the intended meaning clearer.
     Engine families. Proposing to allow engine families to be
divided into subfamilies with respect to CO2. This allowance
would simplify the certification process without changing the overall
requirements.
     Adding a summary of previously applicable emission
standards as Appendix I of part 1036. The proposed new Appendix is
needed for reference to previously applicable emission standards and
will cover regulatory text being deleted from 40 CFR part 86.

C. Heavy-Duty Vehicle GHG Emission Standards and Flexibility

1. Considerations of Aerodynamic Compliance Data
    The aerodynamic drag of a vehicle is determined by the vehicle's
coefficient of drag (Cd), frontal area, air density and
speed. The regulations in Sec.  1037.525 allow manufacturers to use a
range of techniques, including wind tunnel testing, computational fluid
dynamics, and constant speed tests. This broad approach is appropriate
given that no single test procedure is superior in all aspects to other
approaches. However, we also recognized the need for consistency and a
level playing field in evaluating aerodynamic performance. To address
the consistency and level playing field concerns, EPA adopted an
approach that identified coastdown testing as the reference aerodynamic
test method, and specified a procedure to align results from other
aerodynamic test procedures with the reference method by applying a
correction factor (Falt-aero) to results from alternative
methods (Sec.  1037.525(b)).
    With this approach, it is important that Falt-aero be
accurate. Thus, the regulations (Sec.  1037.525(b)) require that
manufacturers use good engineering judgement \7\ when developing
Falt-aero, which would include considering all applicable
coastdown data that are available. The applicable test data would be
those coastdown results that were collected according to the specified
test procedures, whether collected by the manufacturer during
certification and SEAs, or by EPA during confirmatory testing.
---------------------------------------------------------------------------

    \7\ Good engineering judgment means judgments made consistent
with generally accepted scientific and engineering principles and
all available relevant information. See 40 CFR 1068.5 for additional
discussion about applying good engineering judgment.
---------------------------------------------------------------------------

    Consider the hypothetical example shown in the figure below, where
a manufacturer has coastdown results for eight vehicles. The plot shows
the coastdown results corrected to represent wind averaged
CdA, plotted against the corresponding wind average wind
tunnel results. Applying good engineering judgement to such a dataset
would lead a manufacturer to separate the vehicles into two groups,
with each having its own Falt-aero value. The manufacturer
would then need to work with EPA to determine how to appropriately
apply these Falt-aero values to other vehicle
configurations.
    As described in 40 CFR 1037.235, EPA may perform confirmatory
testing on the manufacturer's vehicles, including a vehicle tested to
establish the Falt-aero value. The regulations also include
an interim provision in Sec.  1037.150(s) that states:

    If we conduct coastdown testing to verify your
Falt-aero value for Phase 2 tractors, we will make our
determination using a statistical analysis consistent with the
principles of SEA testing in Sec.  1037.305. We will calculate
confidence intervals using the same equations and will not replace
your test results with ours if your result falls within our
confidence interval or is greater than our test result.

We are proposing to revise the interim allowance in Sec.  1037.150(s)
to require EPA to perform a minimum of 100 valid runs before replacing
a manufacturer's value.
    Test conditions for coastdown testing are another important
consideration. For our testing, EPA intends to minimize the differences
between our test conditions and those of the manufacturer by testing at
similar times of the year. However, because of the limited number of
coastdown test facilities and the challenges of

scheduling time for testing, we cannot commit to testing during the
same season as the manufacturer. In addition, even if we could test
during the same season, we cannot prevent differences in test
conditions.
    Some manufacturers have expressed concern that this approach leaves
too much risk for them because changing an Falt-aero value
would impact a large portion of their production and could undermine
their compliance plans. These manufacturers suggest that EPA should
revise the regulations to provide for larger differences before EPA is
allowed to replace their value. Although we understand this concern, we
do not believe the manufacturers' suggestion would be the appropriate
long-term solution. When multiple measurements provide different
values, good engineering judgment would generally call for more data
rather than selecting a single value. Keeping with this principle, EPA
is requesting comment on a potential allowance for manufacturers to
conduct additional coastdown testing in response to a change by EPA to
their Falt-aero value through a 40 CFR 1068.5 good
engineering judgment request. EPA would attempt to be present to
witness the testing, and potentially take our own measurements. EPA
would follow the procedures under 40 CFR 1068.5 in responding to the
manufacturer to determine an appropriate Falt-aero value,
consistent with good engineering judgment.
    Section 208 of the Act provides EPA broad oversight authority for
manufacturer testing. Consistent with that authority, we are proposing
to add a provision to our regulations at 40 CFR 1037.525(b)(8) to
encourage manufacturers to proactively coordinate with EPA to have
compliance staff present when a manufacturer conducts its coastdown
testing to establish Falt-aero values. Being present for the
testing would give EPA greater confidence that the test was conducted
properly, and thus, would make it less likely that EPA would need to
conduct aerodynamic confirmatory testing on the vehicle. Additionally,
under our current regulations, see 40 CFR 1037.301 and 1037.305, EPA
may require, and generally intends to require for the 2021 model year,
that manufacturers perform SEA testing of at least one of their
reference configurations.
    We are also proposing to revise the minimum number of runs required
for a manufacturer to fail an SEA. Under the current Phase 2
regulations, a manufacturer could fail an SEA after as few as 24 valid
runs. However, review of more recently available indicates that false
failures may occur if the decision is based on 24 runs. Therefore, we
are proposing to require a minimum of 100 valid runs before a vehicle
is deemed to have failed the SEA test.
    While we believe that these changes and clarifications would
largely address the manufacturers' concerns, we request comment on
other possible improvements to the aerodynamic test procedures and
compliance program.
2. Idle Reduction for Tractors
    The Phase 1 version of GEM gives credit for idle emission reduction
technologies that include a tamper-proof automatic engine shutoff
system (AESS), with few override provisions. Phase 2 GEM gives credit
for a wider variety of idle reduction strategies, recognizing
technologies that are available on the market today, such as auxiliary
power units (APUs), diesel fired heaters, and battery powered units.
For example, a tamper-proof AESS with a diesel APU would be credited
with a 4 percent reduction in emissions, while an adjustable AESS with
a diesel fired heater would be credited with a 2 percent reduction in
emissions (See 81 FR 73601, October 25, 2016).
    We now realize that the regulations should also recognize
combinations of these technologies. It is common for sleeper-cab
tractors to include a combination of these technologies to address a
broader range of ambient temperatures. For example, a fuel operated
heater may be used for heating during the winter months, while a
battery APU may be used for air conditioning in the summer. Therefore,
we are proposing to add the following combinations of idle reduction
technologies to Table 9 of Sec.  1037.520. By adding these values to
GEM, it would reduce the compliance burden for manufacturers who would
otherwise need to pursue off-cycle credits for these technology
combinations. The values of the proposed technology benefits were
determined using the same methodology used in the Phase 2 final rule.
8 9
---------------------------------------------------------------------------

    \8\ U.S. Environmental Protection Agency. Greenhouse Gas
Emissions and Fuel Efficiency Standards for Medium- and Heavy-Duty
Engines and Vehicles--Phase 2: Regulatory Impact Analysis. EPA 420-
R-16-900. August 2016. Section <IP_ADDRESS>.1 Idle Control Technologies.
Pages 2-49 through 2-53.
    \9\ Cullen, Angela. Memo to the Docket: Proposed Idle Reduction
Technology Package Benefits. August 2019.

----------------------------------------------------------------------------------------------------------------
                                                Tamper-resistant                         Adjustable
----------------------------------------------------------------------------------------------------------------
                                      Calculated credit                     Calculated credit
       Combination technology                (%)             GEM input             (%)             GEM input
----------------------------------------------------------------------------------------------------------------
Battery APU & Heater................                6.3                  6                5.1                  5
Diesel APU & Heater.................                5.0                  5                4.0                  4
Stop-Start & Heater.................                4.6                  5                3.7                  4
----------------------------------------------------------------------------------------------------------------

3. Manufacturer Testing of Production Vehicles
    The regulations will require tractor manufacturers to annually
chassis test five production vehicles over the GEM cycles to verify
that relative reductions simulated in GEM are being achieved in actual
production. See 40 CFR 1037.665. We do not expect absolute correlation
between GEM results and chassis testing. GEM makes many simplifying
assumptions that do not compromise its usefulness for certification but
do cause it to produce emission rates different from what would be
measured during a chassis dynamometer test. Given the limits of
correlation possible between GEM and chassis testing, we would not
expect such testing to accurately reflect whether a vehicle was
compliant with the GEM standards. Therefore, Sec.  1037.665 does not
apply compliance liability to such testing. Rather, this testing will
be for informational purposes only. (81 FR 73638, October 25, 2016.)
    The regulation also allows manufacturers to request approval of
alternative testing ``that will provide equivalent or better
information.'' Manufacturers have asked us to clarify this allowance.
Therefore, we are proposing to explicitly allow CO2 data

from in-use operation, and CO2 data from manufacturer-run
on-road testing. To qualify, the vehicles would need to be actual
production vehicles rather than custom-built prototype vehicles. Such
vehicles could be covered by testing or manufacturer owned exemptions
but would need to be produced on an assembly line or other normal
production practices. Manufacturers would also need to ensure test
methods are sufficiently similar from year to year to allow for a
meaningful analysis of trends.
4. Canadian Vehicle Standards
    During the Phase 2 rulemaking, Environment and Climate Change
Canada (ECCC) emphasized that the highway weight limitations in Canada
are much greater than those in the U.S. Where the U.S. federal highways
have limits of 80,000 pounds gross combined weight, Canadian provinces
have weight limits up to 140,000 pounds. This difference could
potentially limit emission reductions that could be achieved if ECCC
were to fully harmonize with the U.S.'s HD Phase 2 standards because a
significant portion of the tractors sold in Canada have GCWR (Gross
Combined Weight Rating) greater than EPA's 120,000-pound weight
criterion for ``heavy-haul'' tractors.
    EPA addressed this in Phase 2 by adopting provisions that allow the
manufacturers the option for vehicles above 120,000 pounds GCWR to meet
the more stringent standards that reflect the ECCC views on appropriate
technology improvements, along with the powertrain requirements that go
along with higher GCWR (see 81 FR 73582, October 25, 2016). Vehicles in
the 120,000 to 140,000 pound GCWR range would normally be treated as
simple ``heavy haul'' tractors in GEM, which eliminates the GEM input
for aerodynamics. However, vehicles certified to the optional standards
would be classified as ``heavy Class 8'' tractors in GEM, which then
requires an aerodynamic input. Nevertheless, they both use the heavier
payload for heavy haul.
    ECCC has since adopted final standards for these tractors, which
differ from the optional standards finalized in Phase 2.\10\ Since the
purpose of these standards was to facilitate certification of vehicles
intended for Canada, we are now proposing to revise our optional
standards to be the same as the final ECCC standards. The proposed
standards can be found in Sec.  1037.670. Note that these standards are
not directly comparable to either the normal Class 8 standards or the
heavy haul standards of Sec.  1037.106 because GEM uses different
inputs for them.
---------------------------------------------------------------------------

    \10\ Regulations Amending the Heavy-duty Vehicle and Engine
Greenhouse Gas Emission Regulations and Other Regulations Made Under
the Canadian Environmental Protection Act, 1999: SOR/2018-98, Canada
Gazette, Part II, Volume 152, Number 11, May 16, 2018.
---------------------------------------------------------------------------

    ECCC has also adopted new standards for tractors in the 97,000 to
120,000-pound GCWR category. We request comment on the need for special
provisions for these vehicles.
5. Vehicle Model Year Definition
    For Phase 2 tractors and vocational vehicles, the vehicle's
regulatory model year is usually the calendar year corresponding to the
date of manufacture. However, the Phase 2 regulations allow the
vehicle's model year to be designated to be the year before the
calendar year corresponding to the date of manufacture if the engine's
model year is from an earlier year.
    After promulgation of the FRM, it became apparent that the Phase 2
vehicle model year definition does not allow starting a vehicle model
year before January 1st of the named model year if the engine model
year also begins in the earlier year. For example, if a manufacturer
would start its 2024 engine model year in December 2023, the definition
would not allow vehicles produced in 2023 to be model year 2024.
    To address this issue, EPA is proposing to add back the option to
allow the vehicle's model year to be designated to be the year after
the calendar year of manufacture. In other words, we would allow
manufacturers to meet standards earlier to ensure that engine and
vehicle model years are aligned. Model years would still be constrained
to reflect annual (rather than multi-year) production periods and
include January 1 of the named year.
6. Compliance Margins for GEM Inputs
    The regulations at 40 CFR 1037.620(d) allow components
manufacturers to conduct testing for vehicle manufacturers, but they do
not specify restrictions for the format of the data. Vehicle
manufacturers have raised concerns about component manufacturers
including compliance margins in GEM inputs--in other words, inputting a
value that is significantly worse than the tested result. They state
that many component suppliers are providing GEM inputs with compliance
margins, rather than raw test results. However, when stacked together,
the compliance margins would result in inappropriately high GEM results
that would not represent the vehicles being produced.
    In addressing this concern, it is important to distinguish between
engine fuel maps (which are certified separately) and other GEM inputs
that are not certified. As is discussed in Section I.B.2, certified
engine fuel maps are expected to include compliance margins (albeit
small margins). However, EPA did not expect each GEM input to have a
significant compliance margin of its own. (Note that the aerodynamic
bin structure serves to provide an inherent compliance margin for most
vehicles.) Rather, we expected the certifying OEM to include compliance
margins in their Family Emission Limits (FELs) relative to the GEM
outputs.
    For vehicle GHG standards, the primary role for FEL compliance
margins is to protect against Selective Enforcement Audit (SEA)
failures. Without a compliance margin under the Phase 2 regulations,
normal production variability would cause some vehicles to fail, which
would require the testing of additional vehicles. Even if the family
ultimately passed the SEA, it would probably require the manufacturer
to test a large number of vehicles. However, because SEAs for
particular components would not target GEM inputs for other components,
a modest compliance margin for the FEL would be sufficient to cover the
full range of components.
    While we are not proposing explicit changes with respect to
compliance margins, we are proposing to revise the procedures for
conducting an SEA for an axle or transmission apart from a specific
vehicle. These revisions would further obviate a need for component-
specific compliance margins.
    Although we do not believe that suppliers should normally include
compliance margins when providing test data to OEMs for GEM inputs, we
do believe they should provide to OEMs some characterization of the
statistical confidence they have in their data. This would allow the
OEM to apply an appropriate overall compliance margin for their FEL.
    Finally, none of this is intended to discourage suppliers and OEMs
from entering into commercial agreements related to the accuracy of
test results or SEA performance.
7. SEAs for Axles and Transmissions
    Under 40 CFR 1037.320, a selective enforcement audit (SEA) for
axles or transmissions would consist of performing measurements with a
production axle or transmission to determine mean power loss values as

declared for GEM simulations, and running GEM over one or more
applicable duty cycles based on those measured values. The axle or
transmission is considered passing for a given configuration if the new
modeled emission result for every applicable duty cycle is at or below
the modeled emission result corresponding to the declared GEM inputs.
As described below, EPA is proposing to revise the consequences where
an axle or transmission does not pass.
    We believe special provisions are needed for axles and
transmissions given their importance as compliance technologies and a
market structure in which a single axle or transmission could be used
by multiple certifying OEMs. Under the existing SEA regulations, if an
axle or transmission family from an independent supplier fails an SEA,
vehicle production could be disrupted for multiple OEMs and have
serious economic impacts on them. We are proposing new regulatory text
that would minimize the disruption to vehicle production.
    Under the proposal, if the initial axle or transmission passes,
then the family would pass, and no further testing would be required.
This is the same as under the existing regulations. However, if the
initial axle or transmission does not pass, two additional production
axles or transmissions, as applicable, would need to be tested. Upon
completion of the third test, the results of the three tests would be
combined into a single map. This would become the official test result
for the family. In other words, this proposed approach would correct
the data used by the OEM for their end-of-year report.
    We request comment on whether there are other components for which
this approach would be appropriate.
8. Weight Reduction
    The regulations in 40 CFR 1037.520 include tables to calculate
weight reduction values for using certain lightweight components. The
sum of the weight reductions is used as an input to GEM. EPA is
proposing two changes to Table 8 of that section. First, we are
proposing to allow manufacturers to use the heavy heavy-duty (HHD)
values for medium heavy-duty (MHD) vehicles with three axles (i.e., 6x4
and 6x2 configurations). These MHD vehicles typically share chassis
components with HHD vehicles, but are classified as MHD because of the
lighter duty engines. Second, we are proposing to add a footnote to the
table to clarify that the weight reduction values apply per vehicle
(instead of per component) unless otherwise noted.
9. Electric and Hybrid Vehicles in Vocational Applications
    Manufacturers have expressed concern that the Phase 2 regulations
are not specific enough regarding how to classify hybrid vocational
vehicles (see 40 CFR 1037.140). This is not an issue for tractors,
which are classified based on GVWR. However, vocational vehicles are
generally classified by the class of the engines. Obviously, this
approach does not work for electric vehicle without engines. This
approach could also misrepresent a hybrid vehicle that is able to use
an undersized engine. To address these problems, we are proposing to
revise 40 CFR 1037.140(g) to clarify that hybrid vehicles are heavy
heavy-duty vehicles if they are either propelled by a heavy heavy-duty
engine and all other hybrid and electric vehicles are classified by
GVWR class. We request comment on alternative approaches, such as
specifying the useful life in hours rather than miles for these
vocational vehicles, or allowing electric vehicles to step down one
weight class, with justification from the manufacturer.
10. Vocational Vehicle Segmentation
    The Phase 2 regulatory structure applies the primary vocational
standards by subcategory based on drive cycles. The three subcategories
are Regional, Multi-purpose, and Urban. Manufacturers are generally
allowed to certify vocational vehicles in the particular duty-cycle
subcategory they believe to be most appropriate, consistent with good
engineering judgment. This process for selecting the correct
subcategory is often called ``segmentation.'' Under this structure, EPA
expects manufacturers to choose a subcategory for each vehicle
configuration that best represents the type of operation that vehicle
will actually experience in use. This is important because several
technologies provide very different emission reductions depending on
the actual in-use drive cycle. For example, stop-start would provide
the biggest emission reductions for urban vehicles and much less
reduction for vehicles that operate primary on long intercity drives.
    Manufacturers have raised concerns about the impact of this
structure on their ability to plan for and monitor compliance. They
have suggested that more objective and quantitative good engineering
judgment criteria would be helpful. In response to these concerns, EPA
is proposing an interim ``safe harbor'' provision for vocational
vehicle segmentation. Manufacturers meeting the safe harbor criteria
described below would be presumed to have applied good engineering
judgment.
    The first principle of this safe harbor would be that any vehicle
could be classified as Multi-purpose. The Multi-purpose duty cycle
weighting factors include significant weightings for highway operation,
lower speed transient operation, and idle. Thus, it would not generally
overvalue an individual technology.
    The second principle of this safe harbor would be that vehicles not
classified as Multi-purpose should not be exclusively Regional or
Urban. We are proposing a quantitative measure that evaluates the ratio
of Regional vehicles to Urban vehicles within an averaging set.
Specifically, ratio of Regional vehicles to Urban vehicles must be
between 1:5 and 5:1. An equivalent way of saying this is that the
number of Regional vehicles divided by the number of Urban vehicles
would need to be between 0.20 and 5.0.
    We believe this safe harbor would be consistent with the intent of
the Phase2 program and would not allow manufacturers to reduce the
effective stringency the standards. Nevertheless, EPA requests comment
on this approach overall and the range of acceptable ratios. We also
request comment on how to handle specialty manufacturers that have a
less diverse product offerings. Finally, we request comment on the need
for the subcategory on the label and whether or not we should allow
manufacturers to reassign subcategories for their end-of-year ABT
reports.
11. Early Certification for Small Manufacturers
    Vehicle manufacturers that qualify as small businesses are exempt
from the Phase 1 standards, but must meet the Phase 2 standards
beginning in 2022. However, some vehicle families have been certified
voluntarily to Phase 1 standards by small manufacturers. In an effort
to encourage more voluntary early certification to Phase 1 standards,
we are proposing to adopt a new interim provision in Sec.
1037.150(y)(4) for small manufacturers that certify their entire U.S.-
directed production volume to the Phase 1 standards for calendar year
2021. If the small manufacturers do so, the proposed provision would
then allow these manufacturers to certify to the Phase 1 standards for
model year 2022 (instead of the otherwise applicable Phase 2
standards). Early compliance with the Phase 1 standards should more
than offset any reduction in benefits for model year 2022 (although the
magnitude of any impact on air quality would be small because

of the small production volumes that would be involved).
    The proposed provision would also allow the Phase 1 vehicle credits
that small manufacturers generate from model year 2018 through 2022
vocational vehicles to be used through model year 2027. Under the
existing regulations, all manufacturers that generate credits under the
Phase 1 program are allowed to use such Phase 1 vehicle credits in the
Phase 2 vehicle averaging, banking, and trading program, but the
credits are subject to the five-year credit life. The limit on credit
life can be problematic for small manufacturers with limited product
lines which allow them less flexibility in averaging. We believe the
longer credit life would provide them the flexibility they would need
to ensure all of their products are fully compliant by the time the
Phase 2 standards are fully phased in for model year 2027.
    We request comment on these proposed changes and any potential
impact.
12. Other Minor Heavy-Duty Vehicle Amendments
    EPA is proposing four additional amendments to part 1037:
     Self-contained air conditioning units. We are proposing to
revise Sec.  1037.115(e) to clarify that it is intended to address air
conditioning systems for which the primary purpose is to cool the
driver compartment. This would generally include all complete pickups
and vans, but not self-contained air conditioning or refrigeration
units on vocational vehicles.
     Warranty. We are proposing to revise Sec.  1037.120(b) to
correct the text with respect to tires and Heavy Heavy-Duty vehicles.
     Drayage tractors. We are proposing to revise Sec.
1037.140(aa) to clarify the production limit for drayage tractors under
the custom chassis allowance.
     Neutral idle. We are proposing to revise Sec.
1037.660(a)(2) to specify the permissible delay before engaging neutral
idle when the vehicle is stopped.

D. Requests for Comment on Phase 2 Regulations

    EPA is soliciting comments on other potential amendments, including
those described in this Section II.D. We also welcome comments on the
need for other technical corrections and clarifications. Readers are
reminded to review public comments placed in the docket, which may
contain requests for other corrections and clarifications.
1. Vocational Engines and Credits
    In 40 CFR 1036.150(p), EPA provides special flexibility for engine
manufacturers that certify all their model year 2020 engines within an
averaging set to the model year 2021 FTP and SET standards and
requirements. GHG emission credits those manufacturers generate with
model year 2018 through 2024 engines may be used through model year
2030, instead of being limited to a five-year credit life as specified
in Sec.  1036.740(d). They will also be allowed to certify model year
2024 through 2026 tractor engines to alternative standards that are
slightly higher than the otherwise applicable standards.
    The choice would be made when certifying MY 2020 engines. Instead
of certifying engines to the final year of the Phase 1 engine
standards, manufacturers electing the alternative would indicate that
they are instead certifying to the MY 2021 Phase 2 engine standard.
Because these engine manufacturers would be reducing emissions of
engines otherwise subject to the MY 2020 Phase 1 engine standards (and
because engine reductions were not reflected in the Phase 1 vehicle
program), there would be a net benefit to the environment. These
engines would not generate credits relative to the Phase 1 standards
(that is, MY 2020 engines would only use or generate credits relative
to the pulled ahead MY 2021 Phase 2 engines standards). Because the
vehicle standards themselves are unaffected, these voluntary standards
would not reduce the GHG reductions or fuel savings of the program.
Vehicle manufacturers using the alternative MYs 2024-2026 engines would
need to adopt additional vehicle technology (i.e., technology beyond
that projected to be needed to meet the engine standard) to meet the
applicable vehicle GHG standards. This means the vehicles would still
achieve the same fuel efficiency in use.
    EPA did not adopt a similar provision for alternative MY 2024-2026
standards for vocational engines due to concerns about windfall
credits. However, given our proposed amendment to address these
windfall credits (Section I.B.1), we are asking for comment on the
possibility of a similar set of alternative standards for vocational
engines, as shown in the following table:

--------------------------------------------------------------------------------------------------------------------------------------------------------
               Model years                             Medium heavy-duty vocational                             Heavy heavy-duty vocational
--------------------------------------------------------------------------------------------------------------------------------------------------------
2020-2023...............................  545 g/hp-hr...........................................  513 g/hp-hr.
2024-2026...............................  542 g/hp-hr...........................................  510 g/hp-hr.
--------------------------------------------------------------------------------------------------------------------------------------------------------

    As noted in the Phase 2 FRM, EPA views this type of alternative as
being positive from the environmental and energy conservation
perspectives, while providing significant flexibility for manufacturers
that may reduce their compliance costs. (81 FR 73499, October 25, 2016)
2. Stop-Start Overrides
    Stop-start systems are an important technology to reduce
unnecessary idling, such as when a vehicle is stopped at a traffic
light. In 40 CFR 1037.660, we specify how these systems must operate in
order to qualify for GEM credit. Included among those provisions are
allowances for overriding the automatic engine shutdown where it would
otherwise create a potential system damage or safety issue for the
engine or driver. Manufacturers have asked us to include additional
overrides needed to ensure safe and effective vehicle operation.
Specifically, they have asked us to consider overrides for the
following conditions, which we are requesting comment on:

 Driveline engaged (to prevent driveline and/or starter damage)
 Automatic transmission not in D (to reduce engine and
transmission loading)
 Automatic transmission in P or N (to prevent depleting the
battery)
 Turn signal activated (to prevent engine stop with the vehicle
in intersection)
 Hazard warning signal activated (to prevent engine stop during
limp-home mode)
 SCR thawing (to allow thawing of frozen DEF)
 High steering angle (to avoid steering wheel kickback during
engine start)
 ABS wheel speed sensor failure (to ensure detection of vehicle
speed)
 Hard braking event (to avoid startling the driver after an
event)
 Road grade greater than 7% (to prevent vehicle rollback)

3. Delegated Assembly
    In 40 CFR 1037.621, EPA specifies provisions to allow manufacturers
to ship incomplete vehicles and delegate the final assembly to another
entity. Manufacturers have expressed the concern that these ``delegated
assembly'' requirements are too burdensome in some cases, particularly
in cases such as auxiliary power units and natural gas fuel tanks. EPA
requests comment on this issue.
4. Certification Reporting Requirements
    EPA requests comment on whether and how to revise the text to
simplify or clarify the provisions in 40 CFR 1037.205 that require the
inclusion of GEM results and credit projections in applications for
certification.
5. Mild Hybrid Certification
    Under the Phase 2 regulations, manufacturers must conduct
powertrain testing if they wish to take credit for hybrid systems,
including mild hybrid systems. However, manufacturers have expressed
concerns about the cost of powertrain testing and that the existing
procedure may not measure improvements from certain mild hybrid
systems. EPA requests comment on alternative means of evaluating mild
hybrids. Manufacturers have asked EPA to consider the following
options:
     Allow manufacturers to test a powertrain and apply
analytically-derived scaling factors to others (e.g., scale by fraction
of battery capacity or motor capacity) under 40 CFR 1037.235(h).
     Allow manufacturers to use international test procedures
for battery capacity, motor power, and motor efficiency.
     Provide smaller credit (potentially with a volume limit
and/or only for limited time) in exchange for less testing (e.g.,
reduced benefit when using the simplified model spreadsheet that is
available under docket no. EPA-HQ-OAR-2014-0827-2109).
6. Transmission Calibrations
    Manufacturers with advanced transmission calibrations may use the
powertrain test option in Sec.  1037.550 to demonstrate the performance
of their transmissions. We adopted this option to provide an incentive
for the development of advanced transmissions with sophisticated
calibrations.
    Transmission manufacturers have developed some new efficient
calibrations, but must also maintain less efficient calibrations to
address special types of operation. Due to concerns about resale value,
most customers want to retain the ability to select the correct
calibration for their operation. For transmissions with such selectable
calibrations, Sec.  1037.235(a) requires that they test using the
worst-case calibration, which can undermine the incentive to continue
improving the calibrations. Therefore, we are requesting comment on
allowing manufacturers to measure both the best- and worst-case
calibrations and weight them based on survey data, or other appropriate
means. Commenters are encouraged to address whether such an allowance
would change the effective stringency of the standards.
7. Data Requirements for Hydrogen-Fueled Vehicles
    We request comment on whether special provisions are needed for
hydrogen-fueled vehicles. Currently GEM simulation is required for
these vehicles, although by using a non-carbon fuel, simulating the
vehicle with GEM would result in zero CO2 emissions. We
request comment on whether or not to change our current approach.

E. Other Heavy-Duty Highway Amendments

    This proposed rule includes other amendments related to heavy-duty
highway engines. For example, we are updating the regulations for
certification fees as described in Section III.C. We are also proposing
or soliciting comment on additional amendments as described in the
following sections.
1. Onboard Diagnostics (OBD)
    EPA's OBD regulations for heavy-duty engines are contained in 40
CFR 86.010-18, which was promulgated February 24, 2009 (74 FR 8310).
Although these regulations were originally harmonized with CARB's OBD
program, CARB has made changes to their regulations which EPA has not
adopted. In several cases, CARB has added flexibility to its
regulations. We are requesting comment generally on the differences
between EPA and CARB regulations, in addition to the specific issues
identified below.
    More recently CARB has proposed additional revisions and is
expected to finalize them this year.\11\ We also request comment on
these more recent CARB changes.
---------------------------------------------------------------------------

    \11\ Information is available at https://ww2.arb.ca.gov/rulemaking/2018/heavy-duty-board-diagnostic-system-requirements-2018.
---------------------------------------------------------------------------

    We request comment on the new definitions proposed by CARB at 13
CCR 1971.1(c), including the definitions for ``alternate phase-in'',
``diagnostic or emission critical electronic control unit'', and
``smart device''.
    EPA is requesting comment on California's approach to approving
deficiencies during a model year. In Sec.  1971.1(k)(6.1.1) of their
regulations, CARB states:

    The manufacturer may request a retroactive deficiency until
either of the following dates, whichever is later:
    (A) When the last affected engine or vehicle is produced, or on
December 31 of the calendar year for which the model year is named,
whichever is sooner; or
    (B) 6 months after commencement of the start of engine
production or vehicle production, whichever is later.

    Our current regulations do not allow for retroactive deficiencies.
EPA is requesting comment on whether to adopt CARB's approach.
    We are proposing to adopt the CARB 5% threshold for misfire in
Sec.  86.010-18(g)(2), and to adopt the additional flexibility provided
by CARB for misfires in 13 CCR 1971.1(e)(2.3.3). This would allow
manufacturers to not detect misfires under certain conditions, such as
during aftertreatment regeneration and some low temperature operation.
    We are proposing to revise our in-use compliance standards in Sec.
86.010-18(p) to reflect the CARB approach for minimum ratios for
representative samples. Under the proposed text, an OBD system would
not be considered noncompliant unless a representative sample indicates
the in-use ratio is below 0.088.
    CARB has developed reporting templates for its OBD requirements.
EPA is proposing to allow manufacturers to use these templates for
reporting to EPA, and we are requesting comment on whether regulatory
changes are needed. See CARB Mail-Out #MSC 09-22 as amended on 18-Apr-
2019.
    Our OBD regulations rely on several standard procedures developed
by SAE International, as specified in Sec.  86.010-18(k). The
regulations also reference a standard of the International Organization
for Standardization (ISO). We request comment on the need to update
these procedures to more recent versions as summarized below.

------------------------------------------------------------------------
                                                    Version
                  SAE procedure                    currently    Latest
                                                     cited      version
------------------------------------------------------------------------
SAE J1930.......................................        2002        2017
SAE J1939.......................................        2007        2017
SAE J1939-13....................................        2004        2016
SAE J1939-73....................................        2006        2017
SAE J1962.......................................        2002        2016
SAE J1978.......................................        2002        2002
SAE J1979.......................................        2007        2017
SAE J2012.......................................        2002        2016
SAE J 2403......................................        2007        2014
ISO 15765-4:2005(E).............................        2005        2011
------------------------------------------------------------------------

    In Sec.  86.010-18(l), EPA specifies testing requirements for
demonstrating the performance of monitoring systems. The amount of
testing required depends on the number of engine families a
manufacturer certifies in a given model year. CARB regulations include
equivalent requirements, and our intent is to allow the use of test
data generated for CARB. We are proposing to revise our regulations to
state that CARB-certified configurations do not count as separate
engine families for the purposes of this provision.
    EPA is proposing to revise Sec.  86.010-18(a) and (m) to allow a
simplified carryover OBD certification path intended for special engine
families, such as those certified for export to Canada. This proposed
provision is similar to the allowance to show compliance with Sec.
86.010-18 based on CARB certification. To make use of either
alternative, the manufacturer must demonstrate to the Administrator how
the OBD system they intend to certify meets the intent behind all the
requirements of Sec.  86.010-18.
    These amendments address heavy-duty engines used in vehicles with
GVWR above 14,000 pounds. We request comment on the need for similar
changes for engine-certified heavy-duty engine families subject to 40
CFR 86.007-17 and 86.1806-17.
2. Smoke Standards and Smoke Measurement Procedures
    Diesel heavy-duty highway engines have been subject to smoke
standards in addition to brake-specific emission standards for many
years. The current exhaust emission standards for particulate matter
(PM) cause manufacturers to apply calibrations and emission control
strategies that reduce PM from the exhaust to very low levels. There is
some relationship between brake-specific PM emissions and smoke, but
they are not inherently linked. Nevertheless, modern engines with very
low PM emissions have very low smoke levels when properly maintained.
Thus, we do not believe smoke standards achieve any emission reductions
beyond those that result from DPF-forcing PM standards.
    Manufacturers submit smoke data with certification, but smoke
testing is not required for selective enforcement audits with
production engines. Some state programs continue to rely on smoke
measurement to screen for high-emitting trucks. However, these state
testing programs are separate from EPA certification, so we do not
expect the state programs to depend on EPA certification for smoke
standards. We therefore request comment on removing the smoke standard
as a certification requirement for heavy-duty highway engines. We
particularly request comment on the EPA smoke standard and its
relationship to state testing programs.
    There are also questions about the smoke test procedures. The smoke
test procedures are specified in 40 CFR part 86, subpart I. These
procedures were first adopted almost 50 years ago and have remained
largely unchanged since that time. They currently apply for locomotives
(40 CFR part 1033) and some land-based nonroad diesel engines (40 CFR
part 1039). To the extent these procedures continue to apply, we may
undertake a future rulemaking to update these procedures and include
them in 40 CFR part 1065 along with the other test procedures for
measuring exhaust emissions from test engines. We request comment on
appropriate changes to ensure that these measurement procedures reflect
currently available instruments and practices, without causing the
measured values to redefine the stringency of existing standards.
3. Migration From 40 CFR Part 86, Subpart A
    EPA created 40 CFR part 86 in 1976 to reorganize emission standards
and certification requirements for light-duty and heavy-duty highway
vehicles and engines. In 1985, EPA adopted new standards for heavy-duty
highway engines, codifying the standards in 40 CFR part 86, subpart A,
along with the standards and certification procedures for light-duty
vehicles and light-duty trucks.\12\ Since then, EPA has adopted several
rules to set new and more stringent standards for both light-duty and
heavy-duty emission control programs and to add or revise certification
procedures. However, the original regulatory structure was not well-
suited to handle the number of revisions that occurred over time.
---------------------------------------------------------------------------

    \12\ Emission standards for heavy-duty highway engines were
first adopted by the Department of Health, Education, and Welfare in
the 1960s. These standards and the corresponding certification and
testing procedures were codified at 45 CFR part 1201. In 1972,
shortly after EPA was created as a federal agency, EPA published new
standards and updated procedures while migrating the regulations to
40 CFR part 85 as part of the effort to consolidate all EPA
regulations in a single location.
---------------------------------------------------------------------------

    To improve clarity for regulated parties, EPA has been planning to
migrate the highway heavy-duty engine standards and certification
requirements to 40 CFR part 1036.\13\ We expect to propose that
migration in a separate rulemaking. The general approach will be to
keep the essential regulatory elements in 40 CFR part 86, subpart A,
but to streamline and update the regulatory provisions to align with
best practices and other current provisions that apply for nonroad
engines (such as 40 CFR parts 1033, 1039, and 1042). We believe this
technical amendment rulemaking is a good opportunity to solicit input
on principles and opportunities for eventually adopting those updated
regulations in 40 CFR part 1036.
---------------------------------------------------------------------------

    \13\ 40 CFR part 1036 was created in 2011 as part of the Phase 1
GHG rulemaking (76 FR 57381, September 15, 2011).
---------------------------------------------------------------------------

    The migration of regulatory provisions to 40 CFR part 1036 is
planned for a future rulemaking because it necessitates a thorough
investigation of the provisions that currently apply to heavy-duty
engines under 40 CFR part 86. A memo in the docket for this proposal
describes a range of possible regulatory amendments we could eventually
adopt to reorganize the provisions within 40 CFR part 86, subpart A,
eliminate obsolete content, and improve the readability of the
remaining provisions.\14\ We request comment on those regulatory
changes, and on the value of making these changes in this rulemaking,
considering that these changes will apply only for the limited time
that 40 CFR part 86, subpart A, continues to apply.
---------------------------------------------------------------------------

    \14\ ``Draft Regulatory Text to Update and Reorganize 40 CFR
part 86, subpart A'', EPA memorandum from Alan Stout to Docket EPA-
HQ-OAR-2019-0307, January 23, 2020.
---------------------------------------------------------------------------

III. Other Amendments

A. Ethanol-Blend Test Fuels for Nonroad Spark-Ignition Engines and
Vehicles, Highway Motorcycles, and Portable Fuel Containers

    EPA adopted exhaust and evaporative emission standards for
gasoline-fueled nonroad engines, vehicles, and equipment before there
was a federal gasoline test fuel with 10 percent ethanol (E10). Most of
those programs therefore relied on testing with neat gasoline (E0) or
with a splash-blended mix of neat gasoline and ethanol to make E10. In
the meantime, EPA adopted a federal gasoline test fuel with 10 percent
ethanol for testing motor vehicles (79 FR 23414, April 28, 2014).
    California ARB adopted its own specification for an E10 test fuel
for testing motor vehicles, referred to as ``LEV III E10.'' California
ARB revised its nonroad emission control programs to require
manufacturers to start using LEV III E10 test fuel for certification
starting in model year 2020, without allowing for carryover of previous
data from testing with neat gasoline. California ARB's move to require
use of LEV III E10 test fuel for certification has

led manufacturers to express a concern about the test burden associated
with separate testing to demonstrate compliance with EPA and California
ARB emission standards.
    The concern for aligning test requirements related to test fuel
applies for marine spark-ignition engines (40 CFR part 1045), nonroad
spark-ignition engines above 19 kW (40 CFR part 1048), and recreational
vehicles (40 CFR part 1051).\15\ We expect a similar situation to apply
for highway motorcycles in the 2022-2025 time frame based on California
ARB's plans for further rulemaking activity. In addition, we believe it
is best to update evaporative emission test procedures for equipment
using nonroad spark-ignition engines (40 CFR part 1060) to allow for
using EPA' specified E10 test fuel instead of relying on splash-
blending ethanol with EPA's specified E0 gasoline test fuel (known as
indolene).
---------------------------------------------------------------------------

    \15\ EPA adopted amendments to address these concerns for
nonroad spark-ignition engines at or below 19 kW in an earlier
rulemaking (80 FR 9114, February 19, 2015).
---------------------------------------------------------------------------

    We have issued guidance for marine spark-ignition engines (40 CFR
part 1045) \16\ and for recreational vehicles (40 CFR part 1051) \17\
describing how we may approve certification based on emission
measurements with an E10 test fuel. We are proposing to revise 40 CFR
parts 1045, 1048, and 1051, consistent with the recently issued
guidance documents, to allow for certification based on emission
measurements with EPA's E10 test fuel without requiring EPA approval,
and without adjusting emission standards to account for fuel effects.
For marine spark-ignition engines (40 CFR part 1045), this merely
replaces the existing provision allowing for the alternative of using a
splash-blended E10 test fuel. For recreational vehicles (40 CFR part
1051) and Large SI engines (40 CFR part 1048), naming EPA's E10
specification as the alternative test fuel is a new provision. As
originally adopted for Marine SI engines, EPA would always be able to
do confirmatory testing with either the original E0 test fuel, or the
manufacturer's selected alternative fuel.
---------------------------------------------------------------------------

    \16\ ``Marine Spark Ignition Engine Certification Testing with
California ARB E10 Test Fuel,'' EPA guidance document CD-18-15,
December 24, 2018.
    \17\ ``Off-Highway Recreational Vehicle Certification Testing
with California ARB E10 Test Fuel,'' EPA guidance document CD-19-03,
April 22, 2019.
---------------------------------------------------------------------------

    We are also proposing to allow the same approach for certification
based on emission measurements with EPA's E10 test fuel for highway
motorcycles (including EPA confirmatory testing with either E0 or E10).
    Manufacturers may want to test with California ARB's LEV III E10
test fuel instead of EPA's E10 test fuel. The two sets of fuel
specifications are nearly identical, except that the EPA E10 test fuel
has a higher volatility. For testing hot-stabilized engines, volatility
has a very small effect on exhaust emissions. As a result, we would
expect to approve a manufacturer's request to use LEV III E10 test fuel
instead of EPA's E10 test fuel under 40 CFR 1065.701(b). This provision
allows EPA to approve a different test fuel if it does not affect a
manufacturer's ability to show that its engines will comply with all
applicable emission standards using the fuel specificed in the subpart.
This would apply if fuel's effect on emissions is small enough to allow
for using the test results to show that engines would meet applicable
emission standards with the specified fuel. Since there are no
appreciable fuel effects on exhaust emissions between EPA's E10 test
fuel and LEV III E10 test fuel, we would expect this approval process
to be straightforward.
    We expect this approach of allowing E10 as an alternative test fuel
to adequately address concerns for the identified sectors. Many of
these engines have closed-loop fuel controls that reduce the effect of
fuel variables on exhaust emissions. Many also have relatively large
compliance margins relative to the standards that apply. These factors
help manufacturers confidently test with E10 as an alternative fuel,
knowing that they continue to be liable for meeting emission standards
on the specified E0 test fuel.
    EPA has an interest in transitioning all emission measurements for
gasoline-fueled engines to an E10 test fuel. However, modifying the
emission control program by allowing (or requiring) a complete
compliance demonstration based on an E10 test fuel would require a more
careful assessment of the fuel effects from the ethanol added to the
test fuel. Since the ethanol in some cases has significant effects on
HC, NOX, and CO emissions, we would need to evaluate the
resulting effects on the stringency of the standards. We would
generally expect to adopt adjusted standards with the objective of
maintaining equivalent stringency. Developing such alternative
standards for an E10 test fuel would require a large body of data to
adequately capture the fuel effects on emissions for all the different
classes of highway motorcycles, for all the different types of nonroad
engines and vehicles, and for different kinds of engine technology
within the various sectors. We took this approach for nonroad spark-
ignition engines below 19 kW by adopting alternative CO standards that
apply for testing with LEV III E10 test fuel (78 FR 36397, June 17,
2013).
    Toward that end, we have prepared a memorandum with a collection of
available emission data from nonroad engines and highway motorcycles
tested with E0 and E10 test fuels.\18\ The data include results from
programs conducted by industry associations, EPA efforts with Canadian
labs, and other U.S. laboratory data. We solicit additional emission
data to further help establish the comparison between the test fuels
for different engine types, applications, and technologies. We also
request comment on the benefits or concerns with adopting alternative
standards that correspond with a change to require E10 test fuel for
all testing (both for manufacturers and EPA). Available information
suggests that the fuel-related emission effects for technologies across
these sectors are much more complex and varied than we observed for
Small SI engines. Some technology differences, such as two-stroke vs.
four-stroke and naturally aspirated vs. turbocharged, have relatively
consistent and predictable fuel-related emission effects. However, some
technologies will have fuel-related emission effects that depend on
specific design strategies. For example, manufacturers can use
electronic controls to optimize for power, fuel economy, low-speed
torque, or some other measure of performance. Partial use of closed-
loop control of air-fuel ratios is one clear example of this, with the
potential to adjust the air-fuel ratio to different setpoints, or to
limit closed-loop control only to certain operating conditions. We
request comment on how best to account for these design-specific engine
technologies in evaluating fuel-related emission effects for each type
of engine.
---------------------------------------------------------------------------

    \18\ ``Collection of E0/E10 Emission Data for Current Certified
Nonroad Sector Engines and On Highway Motorcycles'' EPA memorandum
from Cheryl Caffrey to Docket EPA-HQ-OAR-2016-0604, December 6,
2019.
---------------------------------------------------------------------------

    The emission effects are most pronounced for CO emissions, but we
are also interested in HC and NOX emissions. To the extent
that NOX emissions (or HC + NOX emissions)
increase to a degree that affects the stringency of the standards, we
would consider increasing the numerical level of the standard to
maintain equivalent stringency.
    EPA also specifies test fuels for evaporative emission testing. The
gasoline test fuel for measuring

permeation emissions from nonroad fuel tanks and fuel lines is a
splash-blended E10. The is an E0 test fuel that is blended to reach a
10 percent concentration of ethanol. The splash-blended E10 test fuel
is nearly identical to EPA's specified E10 test fuel except for the
volatility. EPA's Tier 3 E10 test fuel has a nominal volatility of 9
psi RVP and the splash-blended E10 has a volatility of about 10 psi
RVP.\19\ We request comment on amending the regulation to allow testing
with the pre-mixed E10 test fuel with 9 psi RVP instead of the splash-
blended E10 test fuel with 10 psi. In particular, we encourage
commenters to share any available data describing how gasoline
volatility affects permeation rates. We would not want manufacturers to
test with lower fuel volatility if it decreases permeation rates and
allows manufacturers to use a less effective control technology. We
also request comment on the level of interest that manufacturers or
testing organizations would have to be able to use EPA's pre-mixed E10
test fuel in the near term, or at any point in the future. We are
concerned about issues related to test burden for manufacturers needing
to meet standards, but we invite commenters to share their insights on
these questions of permeation chemistry. If the final rule includes an
amendment to allow permeation testing with EPA's pre-mixed E10 test
fuel, we would also expect to specify that California ARB's LEVIII E10
test fuel is also acceptable for demonstrating compliance with
permeation standards (see Sec.  1060.505(c)(2)).
---------------------------------------------------------------------------

    \19\ Fuel volatility is based on Reid Vapor Pressure (RVP),
which generally quantifies a fuel's equilibrium vapor pressure at
100 [deg]F. A fuel with volatility of 9 psi would therefore have an
equilibrium vapor pressure of about 9 psi at 100 [deg]F.
---------------------------------------------------------------------------

    A different dynamic applies for diurnal testing. This measurement
procedure applies for Marine SI fuel tanks and for some Large SI
equipment. We currently specify an E0 test fuel with a nominal
volatility of 9 psi RVP for diurnal testing in 40 CFR 1060.525. The
volume of vapor venting during a diurnal test depends on the volatility
of the test fuel. Changing the ethanol content of the fuel without
changing the volatility should cause no significant change in the
volume of vapor venting during the diurnal test. The specified EPA E10
test fuel has the same volatility as the E0 test fuel, but it has the
added ethanol. We request comment on amending the regulation to allow
testing with the specified EPA E10 test fuel instead of the E0 test
fuel. As described for permeation testing above, we would not want
manufacturers to use a test fuel that would decrease vapor pressures
and allow manufacturers to use a less effective control technology. We
also request comment on the level of interest that manufacturers or
testing organizations would have to be able to use EPA's specified E10
test fuel in the near term, or at any point in the future.
    We specify emission standards and test procedures for portable fuel
containers in 40 CFR part 59, subpart F. The test relies on a splash-
blended E10 test fuel. California ARB specifies their LEV III gasoline
test fuel for the analogous procedures in California, but they allow
manufacturers to submit data instead using EPA's specified test fuel.
Accordingly, we believe manufacturers do not face the same burden of
needing to perform duplicate measurements for the two agencies. We are
therefore not proposing to change the EPA test fuel for portable fuel
containers. However, we request comment on allowing manufacturers the
option of using EPA's specified E10 test fuel to demonstrate compliance
with the combined test for diurnal and permeation emissions.

B. Removing Obsolete CFR Content

    EPA first adopted emission standards for light-duty motor vehicles
and heavy-duty highway engines in the 1970s. Emission standards for the
first categories of nonroad engines started to apply in the 1990s. Each
of these programs include emission standards that apply by model year.
For most of these programs over time, engines and vehicles were subject
to increasingly stringent standards and improved certification and
testing requirements. All these standards and regulatory provisions are
codified in the Code of Federal Regulations. As time passes, the
regulations for past model years become obsolete, but it remains in
print until there is a rulemaking change to remove it from print. We
are proposing in this rule to remove large portions of this regulatory
content that no longer applies. The following sections describe these
changes for different sectors.
    Note that Section III.D describes several amendments to emission
control programs for motor vehicles in 40 CFR parts 85 and 86. These
amendments include several provisions that also remove obsolete
regulatory content.
1. Clean Fuel Fleet Standards (40 CFR Part 88)
    The Clean Air Act Amendments of 1990 included numerical standards
for the Clean Fuel Fleet program that were intended to encourage
innovation and reduce emissions for fleets of motor vehicles in certain
nonattainment areas as compared to conventionally fueled vehicles
available at the time. As originally adopted, those Clean Fuel Fleet
standards were substantially more stringent than the standards that
applied to vehicles and engines generally.
    Now that we have begun implementing Tier 3 standards in 40 CFR part
86, subpart S, the Clean Fuel Fleet standards are either less stringent
than or equivalent to the standards that apply to vehicles and engines
generally. Because the statute continues to require Clean Fuel Fleet
standards for state clean-fuel vehicle programs, we cannot simply
remove the Clean Fuel Fleet program from the regulations. Rather, we
are proposing to implement the Clean Fuel Fleet standards in 40 CFR
part 88 with a compliance option where vehicles and engines certified
to current standards under 40 CFR part 86 and part 1036 would be deemed
to comply with the Clean Fuel Fleet standards as Ultra Low-Emission
Vehicles. Further, the Clean Fuel Fleet program as adopted included
labeling requirements for engine and vehicle manufacturers to identify
compliant engines and vehicles, and a restriction against including
such engines or vehicles when calculating emission credits. Both
provisions would also no longer be applicable because of the earlier
mentioned increased stringency of standards for engines and vehicles,
and under the compliance option we are proposing. Therefore, we are
also proposing to remove these regulations. This will give clear
instructions to vehicle and engine manufacturers as well as states that
continue to have Clean Fuel Fleet provisions in their State
Implementation Plans or become subject to these requirements in the
future under CAA sections 182(c)(4)(A) and 246(a).
    For states with areas that become subject to the clean-fuel vehicle
program requirements in the future based on a new designation as an
ozone nonattainment area, the required state implementation plan
submission for the program or for a substitute measure is due within 42
months after the effective date of an area's nonattainment designation.
The clean-fuel vehicle program requirements apply for ozone
nonattainment areas with an initial designation as Serious, Severe, or
Extreme. For marginal and moderate ozone nonattainment areas that are
reclassified as Serious, Severe, or Extreme, the required state
implementation plan submission for the program or for a substitute
measure is due on the date specified in the EPA rulemaking finalizing
the area's reclassification.

    The Clean Fuel Fleet program also depends on vehicle
classifications that include Zero Emission Vehicles and Inherently Low-
Emission Vehicles. We are therefore preserving these defined terms in
40 CFR part 88. We are proposing to consider as Zero Emission Vehicles
all electric vehicles and any vehicle that does not emit
NOX, PM, HC, CO, or formaldehyde (including evaporative
emissions). We are proposing to simplify the definition of Inherently
Low-Emission Vehicles to mean any certified vehicle that is designed to
not vent fuel vapors to the atmosphere.
2. Legacy Nonroad Standards (40 CFR Parts 89 Through 94)
    The 1990 amendments to the Clean Air Act authorized EPA to set
emission standards for nonroad engines. This led to a series of
rulemakings to adopt emission control programs for different nonroad
sectors. From 1994 through 1999, EPA adopted these emission control
programs in 40 CFR parts 89, 90, 91, 92, and 94 (all part of Subchapter
C).
    Starting in 2002, EPA adopted emission standards for additional
nonroad emission control programs in a new subchapter, which allowed
for improved organization and harmonization across sectors. We codified
these new standards and related provisions in 40 CFR parts 1048, 1051,
1065, and 1068 (all part of Subchapter U). Since then, we have migrated
the ``legacy'' emission control programs from Subchapter C to
Subchapter U. In each case, the migration corresponded to new emission
standards and substantially updated compliance and testing provisions.
This applies for the following sectors:

----------------------------------------------------------------------------------------------------------------
                 Sector                        Legacy regulation                   Current regulation
----------------------------------------------------------------------------------------------------------------
Land-based nonroad diesel engines.......  40 CFR part 89.............  40 CFR part 1039.
Nonroad spark-ignition engines at or      40 CFR part 90.............  40 CFR part 1054.
 below 19 kW.
Marine spark-ignition engines...........  40 CFR part 91.............  40 CFR part 1045.
Locomotives and locomotive engines......  40 CFR part 92.............  40 CFR part 1033.
Marine diesel engines...................  40 CFR part 94.............  40 CFR part 1042.
----------------------------------------------------------------------------------------------------------------

    As a result of this migration, engine manufacturers have not
certified engines under the legacy parts for the last 5-10 years.
Removing these legacy parts reduces the cost to the Agency and prevents
confusion for readers who think that the provisions still apply.
    While EPA's engine certification programs don't rely on these
obsolete provisions, the new programs refer to the legacy parts for
some specific provisions. For example, the new standard-setting part
for each type of engine/equipment allows manufacturers to continue to
certify carryover engine families based on test data from procedures
specified in the legacy parts. We are not proposing to discontinue
further use of carryover data from engines originally certified under
the legacy parts. On the other hand, this provision will gradually
sunset itself as manufacturers update engine designs and perform new
testing for their engine families to meet current standards.
Considering California's initiative to disallow carryover for nonroad
spark-ignition engines starting in model year 2021, we request comment
on taking a more direct approach that would sunset carryover based on
testing performed according to the legacy parts.
    Another example of relying on the legacy parts in the new
regulations is emission credits generated under the legacy parts. In
most cases, current programs either disallow using those credits for
certification, or they allow it without keeping separate accounts for
credits generated under the legacy parts. We are proposing no changes
where credits from legacy parts are either unavailable or
indistinguishable from currently generated credits. One exception is
for land-based nonroad diesel engines certified under 40 CFR parts 89
and 1039. Current provisions in Sec.  1039.740 allow for limited use of
Tier 2 and Tier 3 credits from part 89 for certifying Tier 4 engines.
However, these constraints are not time-limited. Now that the Tier 4
standards have been in place for several years, we would be interested
in simplifying the credit accounting by sunsetting these provisions. We
therefore request comment on the extent to which any manufacturers
might rely on continued use of Tier 2 or Tier 3 emission credits for
certifying their land-based nonroad diesel Tier 4 engines.
    We are also aware that other federal and state regulations and
compliance programs include numerous references to 40 CFR parts 89
through 94. To address this, we are proposing to replace the full text
of regulations in the legacy parts with a paragraph describing the
historical scope and purpose for each part. The remaining paragraph
also directs readers to the new regulations that apply in Subchapter U,
and clarifies how the regulatory requirements transition to the new
content. As an example, the statute and regulations prohibit tampering
with certified engines throughout an engine's lifetime, even if the
original text describing that prohibition no longer resides in its
original location in the Code of Federal Regulations.
    We are also proposing to capture the emission standards from the
legacy parts as reference material in an appendix in the appropriate
CFR parts. This allows for readily citing the historical standards in
our own emission control programs, and in any other federal or state
regulations or compliance materials that depend on citing emission
standards that are no longer current for purposes of gaining EPA
certification as part of our nonroad emission control program.
    In addition to removing references to the legacy parts, we are
taking the opportunity to remove additional obsolete content from the
newer regulations. Most of these changes were adopted to address
temporary concerns as part of transitioning to new standards or other
new requirements. We adopted these changes in isolated regulatory
sections as ``interim provisions.'' Most of these interim provisions
have been obsolete for several years.\20\
---------------------------------------------------------------------------

    \20\ A docket memo includes redline text to highlight all the
changes to the regulations in the proposed rule. This is especially
helpful for reviewing provisions that we are removing from the CFR.
See ``Redline Document Showing Proposed Changes to Regulatory Text
in the Heavy-Duty Greenhouse Gas Amendments'', EPA memorandum from
Alan Stout to Docket EPA-HQ-OAR-2019-0307. For obsolete provisions
we are removing, see especially 40 CFR 1027.105, 1033.150, 1042.145,
1045.145, 1048.145, 1051.145, 1054.145, and 1054.625.
---------------------------------------------------------------------------

    References to the legacy parts are especially common for stationary
engines EPA regulates under 40 CFR part 60, subpart IIII and subpart
JJJJ. The emission standards for stationary engines in many cases rely
on current or past nonroad emission standards in 40 CFR parts 89, 90,
and 94. Including all the iterations of these emission standards as