EPA Decision Document:
Off-Cycle Credits for North American
Subaru, Inc*
United State*
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EPA Decision Document:
Off-Cycle Credits for North American
Subaru, Inc*
Compliance Division
Office of Transportation and Air Quality
U.S. Environmental Protection Agency
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Environment; 1 t"r
EPA-420-R-21 -015
June 2021
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EPA Decision Document: Off-Cycle Credits for North
American Subaru, Inc.
I. Introduction
EPA's light-duty vehicle greenhouse gas (GHG) rules include opportunities for manufacturers to generate
C02 credits for technologies that provide C02 reductions not captured by the 2-cycle emissions test.
There are three pathways by which manufacturers can generate off-cycle credits: (1) a pre-determined
"menu" of technologies and credits that is available for 2014 and later model years, (2) a testing-based
option, and (3) an alternative methodology that includes opportunity for public comment. These are
described in more detail in Section II.
Pursuant to those rules North American Subaru, Inc. ("Subaru") submitted applications requesting off-
cycle credits. Subaru applied for high efficiency alternator and pulse width modulated brushless motor
off-cycle GHG credits.
EPA published a notice in the Federal Register on October 5, 2020 announcing a 30-day public comment
period for these applications.1 EPA received no adverse comments regarding the methodologies
presented for determining the credits sought by these manufacturers, and is hereby approving the
technologies, methodologies for determining credits, and credit levels as described in the
manufacturers' applications and in the Federal Register.
Section II of this document provides background on EPA's off-cycle credits program. Section III provides
EPA's decision. This decision document applies only to the applications referenced herein.
II, EPA's Off-cycle Credits Program
EPA's light-duty vehicle greenhouse gas (GHG) program provides three pathways by which a
manufacturer may accrue off-cycle carbon dioxide (C02) credits for those off-cycle technologies that
achieve C02 reductions in the real world but where those reductions are not adequately captured on the
test procedure used to determine compliance with the C02 standards. The first is a predetermined list of
credit values for specific off-cycle technologies that may be used beginning in model year 2014.2 This
pathway allows manufacturers to use conservative credit values established by EPA for a wide range of
technologies, with minimal data submittal or testing requirements. In cases where additional laboratory
testing can demonstrate emission benefits of an off-cycle technology, a second pathway allows
manufacturers to use a broader array of emission tests (known as "5-cycle" testing because the
1 85 FR 62724, October 5, 2020.
2 See 40 CFR 86.1869-12(b).
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methodology uses five different testing procedures) to demonstrate and justify off-cycle C02 credits.3
The additional emission tests allow emission benefits to be demonstrated over some elements of real-
world driving not captured by the GHG compliance tests, including high speeds, hard accelerations, and
cold temperatures. Credits determined according to this methodology do not undergo additional public
review. The third and last pathway allows manufacturers to seek EPA approval to use an alternative
methodology for determining the off-cycle C02 credits.4 This option is only available if the benefit of the
off-cycle technology cannot be adequately demonstrated using the 5-cycle methodology. Manufacturers
may also use this option to demonstrate reductions that exceed those available via use of the
predetermined list.
Under the regulations, a manufacturer seeking to demonstrate off-cycle credits with an alternative
methodology (i.e., under the third pathway described above) must describe a methodology that meets
the following criteria:
• Use modeling, on-road testing, on-road data collection, or other approved analytical or
engineering methods;
• Be robust, verifiable, and capable of demonstrating the real-world emissions benefit with strong
statistical significance;
• Result in a demonstration of baseline and controlled emissions over a wide range of driving
conditions and number of vehicles such that issues of data uncertainty are minimized;
• Result in data on a model type basis unless the manufacturer demonstrates that another basis is
appropriate and adequate.
Further, the regulations specify the following requirements regarding an application for off-cycle C02
credits:
• A manufacturer requesting off-cycle credits must develop a methodology for demonstrating and
determining the benefit of the off-cycle technology and carry out any necessary testing and
analysis required to support that methodology.
• A manufacturer requesting off-cycle credits must conduct testing and/or prepare engineering
analyses that demonstrate the in-use durability of the technology for the full useful life of the
vehicle.
• The application must contain a detailed description of the off-cycle technology and how it
functions to reduce C02 emissions under conditions not represented on the compliance tests.
• The application must contain a list of the vehicle model(s) which will be equipped with the
technology.
• The application must contain a detailed description of the test vehicles selected and an
engineering analysis that supports the selection of those vehicles for testing.
3 See 40 CFR 86.1869-12(c).
4 See 40 CFR 86.1869-12(d).
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• The application must contain all testing and/or simulation data required under the regulations,
plus any other data the manufacturer has considered in the analysis.
Finally, the alternative methodology must be approved by EPA prior to the manufacturer using it to
generate credits. As part of the review process defined by regulation, the alternative methodology
submitted to EPA for consideration must be made available for public comment.5 EPA will consider
public comments as part of its final decision to approve or deny the request for off-cycle credits.
Although these credits are requested under regulatory provisions that don't explicitly require
limitations, or caps, on credit values, EPA is stipulating here that credits for technologies for which there
is a regulatory cap must be held to the applicable regulatory cap, if such credits are approved by EPA.
For example, for reasons described in the implementing rulemaking documents and analyses, EPA
established caps on thermal technology credits of 3.0 grams/mile for cars and 4.3 grams/mile for trucks.
The rationale for these caps is applicable regardless of the off-cycle pathway being used to achieve such
credits. EPA also established caps on technologies that improve the efficiency of air conditioning
systems (5 grams/mile for cars and 7.2 grams per mile for trucks). Thus, credits approved in this Decision
Document are being approved only to the extent that the regulatory caps on credits for certain
technologies or categories of technologies are not exceeded.
III. EPA Decisions on Off-cycle Credit Applications
A. High-Efficiency Alternators
Subaru requested GHG credits for alternators with improved efficiency relative to a baseline alternator,
for the 2017 and later model years. Automotive alternators convert mechanical energy from a
combustion engine into electrical energy that can be used to power a vehicle's electrical systems.
Alternators inherently place a load on the engine, which results in increased fuel consumption and C02
emissions. High efficiency alternators use new technologies to reduce the overall load on the engine yet
continue to meet the electrical demands of the vehicle systems, resulting in lower fuel consumption and
lower C02 emissions. Some comments on EPA's proposed rule for GHG standards for the 2017-2025
model years suggested that EPA provide a credit for high-efficiency alternators on the pre-defined list in
the regulations. While EPA agreed that high-efficiency alternators can reduce electrical load and reduce
fuel consumption, and that these impacts are not seen on the emission test procedures because
accessories that use electricity are turned off, EPA noted the difficulty in defining a one-size-fits-all credit
due to lack of data. Since then, however a methodology has been developed that scales credits based on
the efficiency of the alternator; alternators with efficiency (as measured using an accepted industry
standard procedure) above a baseline value could get credits. Subaru proposed to use this now-
accepted methodology. EPA has previously approved credits for high-efficiency alternators using this
methodology for Ford Motor Company, General Motors Corporation, Fiat Chrysler Automobiles,
5 See 40 CFR 86.1869-12(d)(2).
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Hyundai, Kia, Honda, Nissan and Toyota Motor Company. EPA reviewed the application for
completeness and made it available for public review and comment as required by the regulations.
EPA did not receive any adverse comments on the application from Subaru. EPA received comments
from the Alliance for Automotive Innovation that were supportive and recommended timely approval of
the methodologies for determining off-cycle credits. EPA has evaluated the application and finds that
the methodologies described therein are sound and appropriate. Therefore, EPA is approving the credits
requested by Subaru for the 2017 and later model years. All information necessary to determine the
total Megagrams of credits must be included in the reporting to EPA, and the total Megagrams for each
fleet and model year should be included in a summary of credit averaging, banking, and trading.
The table below shows the credits that have been approved for the high efficiency alternator for Subaru
for model years 2017 and later.
High Efficiency Alternator on % of Baseline Level
VDA efficiency ( % )
Credit (g/mile )
67
0.0
68
0.2
69
0.3
70
0.5
71
0.6
72
0.8
73
1.0
74
1.1
75
1.3
76
1.4
77
1.6
78
1.8
79
1.9
80
2.1
81
2.2
1. Pulse Width Modulat ishless Motor
Using the alternative methodology approach discussed above, Subaru applied for pulse width
modulated (PWM) brushless motor greenhouse gas credits beyond those provided in the regulations.
The PWM brushless motor system uses circuit switching instead of mechanical switching. The
mechanical switching mechanism uses brushes to deliver current to motor windings. By implementing
the brushless motor mechanism, frictional loses are reduced because there is no physical contact
between stator and commutator. There is also a reduction in heat losses with the PWM brushless motor
compared to the mechanical switching motor.
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EPA received comments from the Alliance for Automotive Innovation (AAI) supportive of this application
while disagreeing with Subaru's request to include the A/C on portion under the credit cap.6 AAI claimed
the PWM brushless motor technology most directly affect(s) the operation of a vehicle's electrical
(charging and battery) systems while only indirectly relate(d) to the efficiency of the air conditioning
system itself.
These AAI comments are similar to and reference comments submitted by the Alliance of Automobile
Manufacturers (AAM) on a prior Toyota application for a PWM brushless motor where the Agency found
the A/C credit caps apply when the PWM blower motor is operating when the A/C is 'ON'. EPA found the
comments provided by AAM to be without merit.7
The AAI comments to the Subaru PWM blower motor application did not provide any new arguments
beyond those which the Agency has previously found to be without merit. The Agency is again
concluding that the AAM and the AAI comments on the A/C credit cap not being applicable when the
PWM blower motor is operating and the A/C is 'ON' are without merit.
The following table shows the approved credits for the Subaru brushless motor system for model years
2019 and later.
Brushless Motor
Credits
Total Credit (g
C02/mi)
A/COn (g C02/mi)
A/C Off (g C02/mi)
Manual A/C
0.4
0.2
0.2
Automatic A/C
0.4
0.3
0.1
6 The Alliance for Automotive Innovation represents manufacturers producing cars and light trucks sold in the U.S.
The organization was formed in 2020 and includes motor vehicle manufacturers, original equipment suppliers,
technology and other automotive-related companies and trade associations.
7 EPA Decision Document: Off-Cycle Credits for Toyota Motor North America, EPA-420-R-19-015, October 2019
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