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Alternative Method for Calculating Off-Cycle Credits for Mercedes-Benz Vehicles Under the Light-Duty Greenhouse Gas Emissions Program

American Government Topics:  Mercedes-Benz

Alternative Method for Calculating Off-Cycle Credits for Mercedes-Benz Vehicles Under the Light-Duty Greenhouse Gas Emissions Program

Byron Bunker
Environmental Protection Agency
October 1, 2013

[Federal Register Volume 78, Number 190 (Tuesday, October 1, 2013)]
[Pages 60275-60279]
From the Federal Register Online via the Government Printing Office [www.gpo.gov]
[FR Doc No: 2013-23964]




Alternative Method for Calculating Off-Cycle Credits for 
Mercedes-Benz Vehicles Under the Light-Duty Greenhouse Gas Emissions 

AGENCY: Environmental Protection Agency (EPA).

ACTION: Notice.


SUMMARY: In the light-duty vehicle greenhouse gas rule for model year 
2012 through 2016 vehicles, EPA established a program to allow 
automobile manufacturers to generate ``off-cycle'' carbon dioxide 
(CO2) credits by employing technologies that achieve 
CO2 reductions in the real world but are not appropriately 
captured on the test procedures used by manufacturers to demonstrate 
compliance with the CO2 standards. Under one of the program 
options, a manufacturer may develop and submit to EPA for approval an 
alternative demonstration methodology justifying eligibility for off-
cycle credits and their amount. The regulations concerning off-cycle 
credits require an opportunity for public comment as part of EPA's 
review of such an alternative methodology. EPA is requesting comment on 
an alternative methodology submitted by Mercedes-Benz for determining 
off-cycle credits for the following technologies: engine stop-start, 
high efficiency exterior lighting, infrared glazing, and active seat 
ventilation. The application is only for off-cycle credits for 
Mercedes-Benz vehicles for the 2012 through 2016 model years.

DATES: Comments must be received on or before October 31, 2013.

ADDRESSES: Submit your comments, identified by Docket ID No. EPA-HQ-
OAR-2013-0643, by one of the following methods:
     On-Line at http://www.regulations.gov: Follow the On- Line 
Instructions for Submitting Comments.
     Email: a-and-r-docket@epa.gov.
     Fax: (202) 566-1741.
     Mail: Air and Radiation Docket, Docket ID No. EPA-HQ-OAR-
2013- 0643, U.S. Environmental Protection Agency, Mailcode: 6102T, 1200 
Pennsylvania Avenue NW., Washington, DC 20460. Please include a total 
of two copies.
     Hand Delivery: EPA Docket Center, Public Reading Room, EPA 
West Building, Room 3334, 1301 Constitution Avenue NW., Washington, DC 
20460. Such deliveries are only accepted during the Docket's normal 
hours of operation, and special arrangements should be made for 
deliveries of boxed information.
    On-Line Instructions for Submitting Comments: Direct your comments 
to Docket ID No. EPA-HQ-OAR-2013- 0643. EPA's policy is that all 
comments received will be included in the public docket without change 
and may be made available online at http://www.regulations.gov, 
including any personal information provided, unless the comment 
includes information claimed to be Confidential Business Information 
(CBI) or other information whose disclosure is restricted by statute. 
Do not submit information that you consider to be CBI or otherwise 
protected through http://www.regulations.gov or email.
    The http://www.regulations.gov Web site is an ``anonymous access'' 
system, which means EPA will not know your identity or contact 
information unless you provide it in the body of your comment. If you 
send an email comment directly to EPA without going through http://www.regulations.gov, your email address will automatically be captured 
and included as part of the comment that is placed in the public docket 
and made available on the Internet. If you submit an electronic 
comment, EPA recommends that you include your name and other contact 
information in the body of your comment and with any disk or CD-ROM you 
submit. If EPA cannot read your comment due to technical difficulties 
and cannot contact you for clarification, EPA may not be able to 
consider your comment. Electronic files should avoid the use of special 
characters, any form of encryption, and be free of any defects or 
viruses. For additional information about EPA's public docket visit the 
EPA Docket Center homepage at http://www.epa.gov/epahome/dockets.htm.
    Materials relevant to this proceeding are contained in the Air and 
Radiation Docket and Information Center, maintained in Docket ID No. 
EPA-HQ- OAR-2013-0643. Publicly available docket materials are 
available either electronically through http://www.regulations.gov or 
in hard copy at the Air and Radiation Docket in the EPA Headquarters 
Library, EPA West Building, Room 3334, located at 1301 Constitution 
Avenue NW., Washington, DC. The Public Reading Room is open to the 
public on all federal government work days from 8:30 a.m. to 4:30 p.m.; 
generally, it is open Monday through Friday, excluding holidays. The 
telephone number for the Reading Room is (202) 566-1744. The Air and 
Radiation Docket and Information

[[Page 60276]]

Center's Web site is http://www.epa.gov/oar/docket.html. The electronic 
mail (email) address for the Air and Radiation Docket is: a-and-r-docket@epa.gov, the telephone number is (202) 566-1742, and the fax 
number is (202) 566-9744. An electronic version of the public docket is 
available through the federal government's electronic public docket and 
comment system. You may access EPA dockets at http://www.regulations.gov. After opening the http://www.regulations.gov Web 
site, enter EPA-HQ-OAR-2013-0643 in the ``Enter Keyword or ID'' fill-in 
box to view documents in the record. Although a part of the official 
docket, the public docket does not include Confidential Business 
Information (CBI) or other information whose disclosure is restricted 
by statute.
    EPA will keep the record open until October 31, 2013. All 
information will be available for inspection at the EPA Air Docket No. 
EPA-HQ-OAR-2013-0643. Persons with comments containing proprietary 
information must distinguish such information from other comments to 
the greatest extent possible and label it as ``Confidential Business 
Information'' (``CBI''). If a person making comments wants EPA to base 
its decision on a submission labeled as CBI, then a non-confidential 
version of the document that summarizes the key data or information 
should be submitted to the public docket. To ensure that proprietary 
information is not inadvertently placed in the public docket, 
submissions containing such information should be sent directly to the 
contact person listed below and not to the public docket. Information 
covered by a claim of confidentiality will be disclosed by EPA only to 
the extent allowed, and according to the procedures set forth in 40 CFR 
part 2. If no claim of confidentiality accompanies the submission when 
EPA receives it, EPA will make it available to the public without 
further notice to the person making comments.

FOR FURTHER INFORMATION CONTACT: Roberts French, Environmental 
Protection Specialist, Office of Transportation and Air Quality, 
Compliance Division, U.S. Environmental Protection Agency, 2000 
Traverwood Drive, Ann Arbor, MI 48105. Telephone: (734) 214-4380. Fax: 
(734) 214-4869. Email address: french.roberts@epa.gov.


I. Background

    In the model year (MY) 2012-2016 light-duty vehicle greenhouse gas 
(GHG) rule, EPA established an option for manufacturers to generate 
credits by employing technologies that achieve carbon dioxide 
(CO2) reductions in the real world but are not captured on 
the 2-cycle test procedures used to determine compliance with the fleet 
average standards (i.e., ``off-cycle'' credits). EPA adopted the off-
cycle credit option to encourage the introduction of these types of 
technologies, believing that off-cycle CO2 reductions should 
be considered in determining a manufacturer's fleet average, and that a 
credit mechanism is an effective way to achieve this.
    The MY 2012-2016 rule provided two ways for manufacturers to 
demonstrate the off-cycle emissions reduction capabilities of a 
technology and generate off-cycle credits, either through 5-cycle 
testing (which captures elements of real-world driving not captured by 
the 2-cycle compliance tests, including high speeds, rapid 
accelerations, and cold temperature operation) or an alternative 
demonstration methodology developed by the manufacturer and approved by 
EPA.\1\ The MY 2017-2025 light-duty GHG rule streamlined the off-cycle 
credits program and provided a third pathway for credits, a pre-
determined credits list that may be used beginning in MY 2014.\2\

    \1\ 75 FR 25438-25440, May 7, 2010.
    \2\ 77 FR 62832-62839, October 15, 2012.

    The first pathway for a manufacturer to demonstrate off-cycle 
technology is to conduct 5-cycle emissions testing with and without the 
technology applied to the vehicle.\3\ If the off-cycle emissions 
benefit of the technology is able to be adequately captured through 5-
cycle testing, the manufacturer must conduct testing per the 
regulations, and submit the data to EPA.\4\ This methodology was 
proposed in detail in the rulemakings, which included an opportunity 
for public comment, and therefore manufacturers' applications for 
credits using the 5-cycle process do not undergo additional public 

    \3\ 40 CFR 86.1869-12(c).
    \4\ 40 CFR 86.1869-12(c).

    The second pathway allows manufacturers to demonstrate off-cycle 
emissions reduction technology using an alternative methodology 
developed by the manufacturer in cases where the real world benefit of 
the technology cannot be adequately demonstrated using the 5-cycle test 
procedures.\5\ The regulations regarding the alternative methodology, 
excerpted below, specify the data and information needed to support a 
manufacturer's off-cycle credit application.\6\ The alternative 
methodology must be approved by EPA prior to the manufacturer 
generating credits. Also, as part of the EPA review, the alternative 
methodology must be made available for public comment.\7\ EPA will 
consider public comments as part of its final decision to approve or 
deny the credit request.

    \5\ 40 CFR 86.1869-12(d).
    \6\ 40 CFR 86.1869-12(d) and (e).
    \7\ 40 CFR 86.1869-12(d)(2).

    The regulations for the alternative methodology provided at 40 CFR 
86.1869-12(d)(1)(i)-(iv) specify that the alternative demonstration 
program must be approved in advance by the Administrator and should be 
based on modeling, on-road testing, on-road data collection, or other 
approved analytical or engineering methods, and should be robust, 
verifiable, and capable of demonstrating the real-world emissions 
benefit of the technology with strong statistical significance. 
Further, the alternative program should result in a demonstration of 
baseline and controlled emissions over a wide range of driving 
conditions and vehicles in order to minimize issues of data 
uncertainty. Additionally, the regulations at 40 CFR 86.1869-
12(e)(1)(ii)-(iii) and (e)(2)(i)-(iv) provide specificity regarding the 
data and information that must be submitted to EPA as part of an 
application for credits using an alternative demonstration methodology.
    As noted above, as part of the MY 2017-2025 rule, EPA adopted a 
list of pre-approved off-cycle technologies and credits that 
manufacturers can use beginning in MY 2014.\8\ This third option was 
included in the MY 2017-2025 rule because certain types of off-cycle 
credits are amenable to quantification without further demonstration, 
and EPA's specification of these credits therefore significantly 
streamlines the off-cycle credits program and reduces the testing and 
data burden that the program otherwise entails. Manufacturers using the 
pre-approved list only need to provide EPA at the time of certification 
with information demonstrating that their technology meets applicable 
definitions and qualifies for credits. There are no testing or other 
requirements for demonstrating emissions reductions. Manufacturers may 
however use the 5-cycle or alternative methodology pathways in MY 2014 
and later to demonstrate that their technology achieves greater off-
cycle emissions reductions than are provided by the pre-defined list. 
Also, manufacturers would need to use the 5-cycle or alternative 
methodology pathways to demonstrate eligibility for credits for 

[[Page 60277]]

that are not on the list, as well as the extent of the credits.

    \8\ 40 CFR 86.1869-12(a).

    Mercedes-Benz is applying for credits for model years prior to MY 
2014 and for credits in excess of the credits on the pre-approved list. 
The technologies cannot be adequately demonstrated over the 5-cycle 
test and therefore Mercedes-Benz has applied for credits under the 
alternative methodology approach discussed above.

II. Mercedes-Benz Off-Cycle Credit Application and Alternative 

    Mercedes-Benz has applied for off-cycle credits using the 
alternative demonstration methodology pathway for the following 
technologies: engine stop-start, high efficiency exterior lighting, 
infrared glazing, and active seat ventilation. The application covers 
MY 2012-2016 vehicles. EPA has reviewed the application for 
completeness and is now making the application available for public 
review and comment per the regulations.\9\ The Mercedes-Benz off-cycle 
credit application with confidential business information redacted has 
been placed in docket EPA-HQ- OAR-2013-0643 and on EPA's Web site at 

    \9\ Sec.  86.1869-12(e)(3).

    A summary of Mercedes' alternative methodology for each of the four 
technologies is provided below. For context and comparison, in 
summarizing the Mercedes-Benz alternative methodology, EPA provides 
some background on how the Mercedes-Benz methodology compares to that 
developed by EPA in the MY 2017-2025 light-duty GHG rulemaking for the 
pre-approved list of off-cycle credits, which is contained in the Joint 
Technical Support Document (TSD), Chapter 5.\10\

    \10\ Joint Technical Support Document: Final Rulemaking for 
2017-2025 Light-duty Vehicle Greenhouse Gas Emission Standards for 
Corporate Average Fuel Economy Standards, United States 
Environmental Protection Agency and National Highway Traffic Safety 
Administration, August 2012, EPA-420-R-12-901.

A. Engine Stop-Start

    Mercedes-Benz is applying for engine idle stop-start credit 
covering all of their MY 2012-2016 U.S. model product range (e.g., 
small/mid-size/large cars and light-duty trucks) (See Section II-III of 
Mercedes-Benz Application). Mercedes-Benz is following a similar 
methodology to the one EPA described in the TSD for the MY2017-2025 
rule, but with unique inputs for idle time and stop-start system 
effectiveness which includes parameters related to Mercedes' unique 
control strategy for its stop-start system.\11\

    \11\ MY2017-2025 Technical Support Document, Chapter 5, Section

    The basic methodology entails the following steps: estimate or 
measure the total idle fraction as a percentage of all vehicle 
operation in the real-world; estimate or measure the percentage of idle 
fraction that the stop-start system is enabled out of all the available 
idle time (i.e., eligible stop-start percentage or stop-start system 
effectiveness); determine the benefit of the stop-start system in grams 
per mile based on A-B testing (i.e., technology on and off); and 
multiply the eligible real world stop-start time (relative to the 2-
cycle eligible time) by the stop-start system benefit to estimate the 
engine idle stop-start credit.
    In lieu of the EPA default idle time derived from the MOVES model, 
Mercedes-Benz is proposing to apply a unique idle time specific to its 
vehicles. To estimate the total idle time as a percentage of all 
vehicle operation, Mercedes-Benz conducted a field study in calendar 
years 2010-2011 including 29 instrumented customer vehicles, randomly 
selected from the Mercedes-Benz customer base. The field study was 
performed for a period of 13 months in eight states: California, New 
York, New Jersey, Florida, Texas, Illinois, Virginia, and Arizona. 
These eight states represented about 65% of the Mercedes-Benz sales 
volume. The remaining 35% of the Mercedes-Benz sales fleet was 
distributed in the other 42 states not included in the idle fraction 
study. During the course of the study, the vehicles accumulated 311,118 
miles. The 29 vehicle sample broadly represents the Mercedes-Benz 
models equipped with stop-start technology sold in the United States. 
Based on this study, Mercedes-Benz estimated that its vehicles have a 
23.83% total idle fraction as a percentage of all vehicle operation.
    To provide further support for its idle fraction estimate, 
Mercedes-Benz acquired an independent estimate of idle fraction for its 
vehicles from Progressive Insurance. Progressive Insurance has about 
1.4 million vehicles in its ``Snapshot'' Program covering 44 states 
(excluding California, North Carolina, Tennessee, Indiana, Arkansas, 
and Hawaii), over a six month period.\12\ In the Progressive data set, 
there are 17,484 Mercedes-Benz vehicles which are represented in 
proportion to current industry sales shares. Based on the Progressive 
data set, the Mercedes-Benz vehicles are estimated to have an idle 
fraction of 23.9%. This is almost exactly the same as the 23.83% idle 
fraction found in the Mercedes-Benz study discussed above and used by 
Mercedes-Benz in their analysis. Further, since the Progressive 
Insurance data covers 37 out of the other 42 states not included in the 
Mercedes-Benz idle fraction study, this data implies that the other 35% 
of the sales volume not represented by the Mercedes-Benz data has 
consistent idle fractions. Mercedes indicated that none of the other 42 
states, except for Pennsylvania, have equivalent sales volumes to the 
states used in the idle fraction study. As such, Mercedes-Benz 
concludes that the idle fraction for the other 35% of the sales volume, 
if different, would not have significantly altered the idle fraction 

    \12\ Of these states, only California is a major market for 

    To estimate the percentage of idle fraction during which the stop-
start system is enabled, Mercedes-Benz used EPA's methodology in 
Chapter 5 of the Technical Support Document (TSD) for the MY2017-2025 
rule, with inputs specific to Mercedes-Benz vehicles and control 
    The following background is provided to give some additional 
context on how EPA derived off-cycle credits for stop-start systems for 
the pre-approved menu in the MY 2017-2025 rulemaking. EPA constrained 
stop-start system effectiveness based on three operating temperature 
ranges: cold temperatures below 40 degrees Fahrenheit, mid-temperatures 
between 40 and 80 degrees Fahrenheit, and hot temperatures above 80 
degrees. For the cold temperature range, EPA assumed that passenger 
demand for heat would reduce stop-start effectiveness unless the 
vehicle possesses an electric heater circulation pump, or equivalent 
system, that supplies sufficient heat during engine off operation. For 
the hot temperature range, EPA assumed that passenger demand for air 
conditioning (A/C) would render the stop-start system inoperable, 
unless the manufacturer has some supplemental system to support cabin 
cooling. For all the temperature ranges, EPA assumed that the stop-
start system always defaults on when the vehicle is keyed on. EPA 
assumed the overall system effectiveness would be reduced to 87.75% due 
to these temperature effects.
    Mercedes Benz's stop-start system has several design features that 
differ from those used by EPA for the pre-approved menu analysis. As 
described in Section III of the Mercedes-Benz application, Mercedes-
Benz took these factors into account in analyzing its system 
performance. First, the Mercedes-Benz stop-start system includes an 

[[Page 60278]]

heater circulation pump that maintains cabin heating in cold 
temperatures, and thus enables stop-start capability when heat is 
demanded. Second, the Mercedes-Benz system has a supplemental 12 volt 
battery system that supplies power for all the electrical components 
and accessories. This allows the main battery to support restarting and 
also enables stop-start capability even when A/C is demanded. Mercedes-
Benz also made an adjustment to account for OBD and stop-start 
interactions, which limits the availability of stop-start during the 
first 170 seconds of vehicle operation. These adjustments resulted in 
an estimated fraction of effectiveness (i.e., when the system is 
active) of about 91.32%, compared to EPA's generic estimate of 87.75%.
    In addition, the Mercedes-Benz system includes an ``EcoButton'' 
that allows customers to disable the stop-start system. An estimate of 
the frequency of use of the EcoButton to disable the stop-start system 
is included in the Mercedes-Benz calculations. Finally, the Mercedes-
Benz stop-start system has a maximum engine off duration of three 
minutes; therefore, the stop-start system would not be active after an 
idle period exceeds three minutes. Based on these features, Mercedes-
Benz reduced its eligible idle time of 23.83% to a total eligible idle 
time of 21.22% using the 91.32% system effectiveness discussed above, 
and an additional discount of 2.5% for EcoButton usage and idles 
exceeding the Mercedes-Benz system's 3 minute engine off duration.
    To determine the CO2 emissions benefit of the stop-start 
system, Mercedes-Benz performed testing of Mercedes-Benz vehicles 
equipped with stop-start in different vehicle categories with the stop-
start system on and off. Based on this testing, Mercedes-Benz measured 
a benefit of: 9.8 g/mi CO2 for small size cars, 8.1 g/mi 
CO2 for mid-size cars, 16.9 g/mi CO2 for large 
size cars, and 15.2 g/mi CO2 for light-duty trucks (e.g., 
SUVs). These g/mile GHG improvement values reflect the operational 
effectiveness of the Mercedes-Benz system during the 2-cycle testing. 
The effectiveness (i.e., the time the engine is off compared to the 
total idle time in the cycle) of the stop-start system over the 2-cycle 
test ranged from 67.3% to 80.4%.
    Based on the eligible stop-start idle fraction of 21.22%, compared 
with 10% idle fraction over the 2-cycle tests, and the emissions 
benefits measured above, Mercedes-Benz calculated an engine stop-start 
credit of 11.0 g/mi CO2 for small size cars; 9.1 g/mi 
CO2 for mid-size cars; 19.0 g/mi CO2 for large 
size cars; and 17.1 g/mi CO2 for light-duty trucks (for 
example, for small cars, these credits were derived as: (9.8 g/mi 
CO2 x 0.2122/0.10) - 9.8 g/mi CO2 = 11.0 g/mi 
High Efficiency Exterior Lighting
    Mercedes-Benz is applying for off-cycle credits for high efficiency 
exterior lighting for their MY 2012-2016 U.S. model product range with 
the following lighting elements: low beam head lights, high beam head 
lights, parking/position, front turn signal, front side marker, tail 
lights, rear turn signal, and license plate (See Section IV of the 
Mercedes-Benz application). This list of lighting elements is 
consistent with that specified by EPA for the pre-approved list in the 
MY 2017-2025 rule.\13\

    \13\ 40 CFR 86.1869-12(a)(ii).

    To calculate the high efficiency exterior lighting credits, 
Mercedes-Benz used the EPA methodology set forth in the TSD for the 
MY2017-2025 rule.\14\ Specifically, Mercedes-Benz used the MY 2017-2025 
rule baseline wattage values for each lighting element listed above and 
the time of day (e.g., day time, night time) usage rates from a study 
performed by Schoettle et al. \15\ and inserted the wattage values from 
the Mercedes-Benz high efficiency exterior lighting to determine the 
wattage savings for each lighting element. In most cases, the Mercedes-
Benz wattage savings for each lighting element exceeded the wattage 
savings projected in the MY 2017-2025 rule (exceptions: parking/
position lights at 70% savings versus 78% in the MY 2017-2025 rule; 
license plate light at 86% versus 90% in the MY 2017-2025 rule).

    \14\ MY2017-2025 Technical Support Document, Chapter 5, Section 
    \15\ Schoettle, B., et al., ``LEDS and Power Consumption of 
Exterior Automotive Lighting: Implications for Gasoline and Electric 
Vehicles,'' University of Michigan Transportation Research 
Institute, October, 2008. For the MY2017-2025 Rule, the high 
efficiency exterior lighting wattage for one lighting element, low 
beam head lights, was revised based on manufacturer comment.

    For the final credit amounts, Mercedes-Benz multiplied the wattage 
savings times the usage rates and a constant of 0.032 g/mi 
CO2/watt (based on data showing a 100 watt savings equates 
to 3.2 g/mi CO2 savings) for a credit of 1.1 g/mi 
CO2 total for all the high-efficiency exterior lighting 
elements used over the range of Mercedes-Benz models. In comparison, 
the default credit value for high efficiency exterior lighting in the 
MY2017-2025 rule is 1.0 g/mi CO2.
Infrared Glazing
    Mercedes-Benz is applying for off-cycle credits for infrared 
glazing for the MY 2012-2013 S-Class, ML-Class and GL-Class vehicles 
that utilize infrared glazing technology (See Section IV of Mercedes-
Benz's application). The infrared glazing technology absorbs and/or 
reflects a percentage of the infrared solar energy emitted from the sun 
and reduces the amount of solar heat load transmitted into the cabin; 
this is termed ``total solar transmittance'' or ``Tts.'' The Tts is 
usually expressed as a percentage and defined as the amount of solar 
energy that passes through the glazing, including energy absorbed and 
subsequently re-radiated to the interior, to the amount of solar energy 
imparted on the surface of glazing.\16\ The higher this number, the 
more solar energy is allowed to penetrate into the passenger cabin. 
Therefore, a lower Tts number is better since less solar energy will 
penetrate the passenger cabin and, consequently, the interior cabin 
temperature is reduced. Infrared glazing technologies improve passenger 
comfort, reducing the need for air conditioning (A/C) usage, which in 
turn, reduces vehicle fuel consumption. EPA's analysis relied on a 
study performed by the National Renewable Energy Laboratory (NREL) 
demonstrating that a one degree centigrade reduction in cabin air 
temperature results in a 2.2% reduction in CO2 emissions 
resulting from a reduction in passenger compartment temperature and 
reduced A/C usage.\17\

    \16\ Title 17 California Code of Regulations Sec.  95600-95605: 
``Cool Car Standards and Test Procedures--2012 and Subsequent Model-
Year Passenger Cars, Light-Duty Trucks, and Medium-Duty Vehicles.''; 
Air Resources Board; May 8, 2009 (see:http://www.arb.ca.gov/regact/2009/coolcars09/coolcarsappa.pdf).
    \17\ Rugh, J., Farrington, R. ``Vehicle Ancillary Load Reduction 
Project Close-Out Report,'' National Renewable Energy Laboratory 
Technical Report NREL/TP-540-42454, January, 2008.

    To calculate the infrared glazing credits, Mercedes-Benz used the 
methods set forth in Chapter 5 of the TSD for the MY 2017-2025 
rule.\18\ This method utilizes the International Organization for 
Standardization's (ISO) standard 13837 for measuring the solar 
transmittance of infrared glazing \19\ and a formula for estimating the 
effect of the solar performance of glazing technologies developed by 
EPA and California Air Resources Board with

[[Page 60279]]

input from the National Renewable Energy Laboratory (NREL) and the 
Enhanced Performance Glass Automotive Association (EPGAA). 
Specifically, the contribution of each glass/glazing location to the 
overall interior temperature reduction is estimated using its measured 
Tts, relative to a baseline level, and the area of the glass/glazing 
location relative to the overall glass area. \20\

    \18\ MY2017-2025 Technical Support Document, Chapter 5, Section 
    \19\ International Organization for Standardization's (ISO) 
13837: ``Road vehicles--Safety glazing materials--Method for the 
determination of solar transmittance,'' April 15, 2008.
    \20\ 40 CFR 86.1869-12(b)(1)(viii)(A).

    The infrared glazing used by Mercedes-Benz has the same Tts 
performance levels as the baseline Tts levels specified in the MY2017-
2025 rule: 62% for all glazing locations, except for rooflites and rear 
side glazings of crossovers, SUVs, and minivans, which have a baseline 
Tts of 40%. Based on the Tts levels for Mercedes Benz's infrared 
glazing and the formula described above, Mercedes-Benz calculated a 
credit of 0.8 to 1.7 g/mi CO2 for the infrared glazing used 
over the range of Mercedes-Benz models. In comparison, the default 
credit values for infrared glazing in the MY2017-2025 rule are scalable 
depending on such factors as the amount of glass in the vehicle and the 
performance of the glazing, up to a maximum of 2.9 g/mi CO2 
for cars and 3.9 g/mi CO2 for trucks.
Active Seat Ventilation
    Mercedes-Benz is applying for off-cycle credits for applicable 
vehicles that have active seat ventilation on both the front row' 
driver and passenger seats (See Section IV of Mercedes-Benz's 
application).\21\ The Mercedes-Benz active seat ventilation technology 
has the capability to both pull air away from and push air to the 
seating surface.

    \21\ 40 CFR 86.1869-12(b)(4)(viii).

    To calculate the active seat ventilation credits, Mercedes-Benz 
used the methods set forth in Chapter 5 of the MY 2017-2025 TSD.\22\ 
Based on the NREL study mentioned above, a 7.5% reduction in air 
conditioning (A/C) related emissions could be achieved by lowering the 
surface temperature of the vehicle seats.\23\

    \22\ MY2017-2025 Technical Support Document, Chapter 5, Section 
    \23\ Ibid 12.

    Based on the seat location criteria, capability, and the 
methodology described above, Mercedes-Benz estimated a credit of 1.0 g/
mi CO2 for cars and 1.3 g/mi CO2 for trucks for 
the active seat ventilation technology used over the range of Mercedes-
Benz models. These values are identical to the default values in the 
pre-approved off-cycle credit list in the MY 2017-2025 rule. Therefore, 
Mercedes-Benz concludes that its active seat ventilation system 
achieves equivalent performance to that assumed in the MY 2017-2025 
rule. Mercedes-Benz could use the pre-approved list to claim these 
credits beginning in MY 2014, but since they are seeking credits to 
begin in MY 2012, and because these technologies are not measurable 
through the 5-cycle testing pathway, Mercedes-Benz is applying for 
these credits through this alternative technology pathway.

III. EPA Decision Process

    EPA is providing a 30-day comment period on this application for an 
alternative methodology for off-cycle credits, as specified by the 
regulations. The manufacturer may submit a written rebuttal of comments 
for EPA's consideration, or may revise its application in response to 
comments; EPA would review a revised application as if it were a new 
application.\24\ After reviewing any public comments and any rebuttal 
of comments submitted by Mercedes-Benz, EPA will make a final decision 
regarding the credit request. EPA will make its decision available to 
the public by placing a decision document in the docket as specified in 
the MY 2017-2025 rule.\25\ and on EPA's Web site at http://www.epa.gov/otaq/regs/ld-hwy/greenhouse/ld-ghg.htm.

    \24\ 40 CFR 86.1869-12(e)(3)(iii).
    \25\ 40 CFR 86.1869-12(e)(4)(iii).

    An EPA decision to approve Mercedes Benz's off-cycle credit request 
would only apply to the vehicles specified in the Mercedes-Benz 
application for MYs 2012-2016. Such decision would not apply to other 
Mercedes-Benz vehicles or vehicles from other manufacturers. While the 
broad methodology used by Mercedes-Benz could potentially be used for 
other vehicles and by other manufacturers, the vehicle specific data 
needed to demonstrate the off-cycle emissions reductions would likely 
be different. In such cases, a new application would be required, 
including an opportunity for public comment.

    Dated: September 20, 2013.
Byron Bunker,
Director, Compliance Division, Office of Transportation and Air 
Quality, Office of Air and Radiation.
[FR Doc. 2013-23964 Filed 9-30-13; 8:45 am]

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