40 C.F.R. § 600.210-08 : Protection of Environment — ENVIRONMENTAL PROTECTION AGENCY — ENERGY POLICY — FUEL ECONOMY AND GREENHOUSE GAS EXHAUST EMISSIONS OF MOTOR VEHICLES — PROCEDURES FOR CALCULATING FUEL ECONOMY AND CARBON-RELATED EXHAUST EMISSION VALUES —08 - Calculation of fuel economy values for labeling

(a) General labels. Except as permitted in paragraph (e) of this section, fuel economy for general labels can be determined by two methods. The first is based on vehicle-specific model-type 5-cycle data as determined in §600.209-08(b). This method is optional beginning in the 2008 model year for all vehicles, including medium-duty passenger vehicles, and required beginning in the 2011 model year (except for dedicated alternative-fuel vehicles, dual fuel vehicles when operating on alternative fuel, and medium duty passenger vehicles) unless otherwise indicated according to the provisions in § 600.115-08. The second method is the derived 5-cycle method, and is based on fuel economy that is derived from vehicle-specific 5-cycle model type data as determined in paragraph (a)(2) of this section. This method is required for 2008 through 2010 model years (except for medium-duty passenger vehicles, in which case it is optional), and is permitted beginning in 2011 model year under the provisions of § 600.115-08. If the manufacturer determines that the resulting label values from either of these methods are not representative of the fuel economy for that model type, they may voluntarily lower these values. All 2011 and later model year medium-duty passenger vehicles, dedicated alternative-fueled vehicles, and dual fuel vehicles when operating on alternative fuel must be labeled for fuel economy, using the derived 5-cycle method or, at the manufacturer's option, the vehicle-specific 5-cycle method. Fuel economy label values for dual fuel vehicles operating on alcohol-based or natural gas fuel are calculated separately.
(1) Vehicle-specific 5-cycle labels. The city and highway model type fuel economy determined in §600.209-08(b), rounded to the nearest mpg, comprise the fuel economy values for general fuel economy labels, or, alternatively;
(2) Derived 5-cycle labels. Derived 5-cycle city and highway label values are determined according to the following method:
(i) For each model type, determine the derived five-cycle city fuel economy using the following equation and coefficients determined by the Administrator:

Where:

City Intercept = Intercept determined by the Administrator based on historic vehicle-specific 5-cycle city fuel economy data.

City Slope = Slope determined by the Administrator based on historic vehicle-specific 5-cycle city fuel economy data.

MT FTP FE = the model type FTP-based city fuel economy determined under §600.208-08(b), rounded to the nearest 0.0001 mpg.

(ii) For each model type, determine the derived five-cycle highway fuel economy using the equation below and coefficients determined by the Administrator:

Where:

Highway Intercept = Intercept determined by the Administrator based on historic vehicle-specific 5-cycle highway fuel economy data.

Highway Slope = Slope determined by the Administrator based on historic vehicle-specific 5-cycle highway fuel economy data.

MT HFET FE = the model type highway fuel economy determined under §600.208-08(b), rounded to the nearest 0.0001 mpg.

(iii) For 2008 and later model year vehicles, unless and until superseded by written guidance from the Administrator, the following intercepts and slopes shall be used in the equations in paragraphs (a)(2)(i) and (a)(2)(ii) of this section:

City Intercept = 0.003259.

City Slope = 1.1805.

Highway Intercept = 0.001376.

Highway Slope = 1.3466.

The Administrator will periodically update the slopes and intercepts via guidance and will determine the model year that the new coefficients must take effect. The Administrator will issue guidance no later than six months prior to the earliest starting date of the effective model year (e.g., for 2011 models, the earliest start of the model year is January 2, 2010, so guidance would be issued by July 1, 2009.) Until otherwise instructed by written guidance from the Administrator, manufacturers must use the coefficients that are in currently in effect.

(3) General alternate fuel label values for dual-fueled vehicles.
(i) City and Highway label values for dual fuel alcohol-based and natural gas vehicles when using the alternate fuel are separately determined by the following calculation:

Where:

FEalt = The unrounded FTP-based model-type city or HFET-based model-type highway fuel economy from the alternate fuel, as determined in § 600.208 (b)(5)(ii).

5-cycle FEgas = The unrounded vehicle-specific or derived 5-cycle model-type city or highway fuel economy, as determined in paragraph (a)(1) or (a)(2) of this section.

FEgas = The unrounded FTP-based city or HFET-based model type highway fuel economy from gasoline (or diesel), as determined in § 600.208 (b)(5)(i).

The result, rounded to the nearest whole number, is the alternate fuel label value for dual fuel vehicles.

(ii) Optionally, if complete 5-cycle testing has been performed using the alternate fuel, the manufacturer may choose to use the alternate fuel label city or highway value result in §600.209-08(b)(5)(ii), rounded to the nearest whole number.
(b) Specific Labels. The following two methods are used to determine specific labels. The first is based on vehicle-specific configuration 5-cycle data as determined in §600.207-08. This method is optional beginning in the 2008 model year for all vehicles, including medium-duty passenger vehicles, and required beginning in the 2011 model year (except for medium-duty passenger vehicles) unless otherwise indicated according to the provisions in § 600.115-08. The second method is based on derived 5-cycle configuration data as determined in paragraph (a)(2) of this section. This method is required for 2008 through 2010 model years (except for medium-duty passenger vehicles, in which case it is optional), and is allowed beginning in 2011 model year if permitted under the provisions in § 600.115-08. If the manufacturer determines that the resulting label values from either of these methods are not representative of the fuel economy for that model type, they may voluntarily lower these values. All 2011 and later model year medium-duty passenger vehicles must be labeled for fuel economy, using the derived 5-cycle method or, at the manufacturer's option, the vehicle-specific 5-cycle method. Fuel economy label values for dual fuel vehicles operating on alcohol-based or natural gas fuel are calculated separately.
(1) Vehicle-specific 5-cycle labels. The city and highway configuration fuel economy determined in §600.207-08, rounded to the nearest mpg, comprise the fuel economy values for specific fuel economy labels, or, alternatively;
(2) Derived 5-cycle labels. Specific city and highway label values from derived 5-cycle are determined according to the following method:
(i) Determine the derived five-cycle city fuel economy of the configuration using the equation below and coefficients determined by the Administrator:

Where:

City Intercept = Intercept determined by the Administrator based on historic vehicle-specific 5-cycle city fuel economy data.

City Slope = Slope determined by the Administrator based on historic vehicle-specific 5-cycle city fuel economy data.

Config FTP FE = the configuration FTP-based city fuel economy determined under §600.206-08, rounded to the nearest tenth.

(ii) Determine the derived five-cycle highway fuel economy of the configuration using the equation below and coefficients determined by the Administrator:

Where:

Highway Intercept = Intercept determined by the Administrator based on historic vehicle-specific 5-cycle highway fuel economy data.

Highway Slope = Slope determined by the Administrator based on historic vehicle-specific 5-cycle highway fuel economy data.

Config HFET FE = the configuration highway fuel economy determined under §600.206-08, rounded to the nearest tenth.

(iii) The slopes and intercepts of paragraph (a)(2)(iii) of this section apply.
(3) Specific alternate fuel label values for dual-fueled vehicles.
(i) Specific city and highway label values for dual fuel alcohol-based and natural gas vehicles when using the alternate fuel are separately determined by the following calculation:

Where:

FEalt = The unrounded FTP-based configuration city or HFET-based configuration highway fuel economy from the alternate fuel, as determined in § 600.206.

5cycle FEgas = The unrounded vehicle-specific or derived 5-cycle configuration city or highway fuel economy as determined in paragraph (b)(1) or (b)(2) of this section.

FEgas = The unrounded FTP-based city or HFET-based configuration highway fuel economy from gasoline, as determined in §600.206-08.

The result, rounded to the nearest whole number, is the alternate fuel label value for dual fuel vehicles.

(ii) Optionally, if complete 5-cycle testing has been performed using the alternate fuel, the manufacturer may choose to use the alternate fuel label city or highway value result in §600.207-08(a)(4)(ii), rounded to the nearest whole number.
(c) For the purposes of calculating the combined fuel economy for a model type, to be used in displaying on the label and for determining annual fuel costs under § 600.307-08, the manufacturer shall:
(1)
(i) For gasoline-fueled, diesel-fueled, alcohol-fueled, and natural gas-fueled automobiles, and for dual fuel automobiles operated on gasoline or diesel fuel, harmonically average the unrounded city and highway values, determined in paragraphs (a)(1) or (2) of this section and (b)(1) or (2) of this section, weighted 0.55 and 0.45 respectively, and round to the nearest whole mpg. (An example of this calculation procedure appears in appendix II of this part); or
(ii) For alcohol dual fuel and natural gas dual fuel automobiles operated on the alternate fuel, harmonically average the unrounded city and highway values from the tests performed using the alternative fuel as determined in paragraphs (a)(3) and (b)(3) of this section, weighted 0.55 and 0.45 respectively, and round to the nearest whole mpg.
(d)
(1) Label values for 2008-2010 model year automobiles (except medium-duty passenger vehicles) the city and highway values for a model type must be determined by the same method. If the manufacturer optionally chooses to determine fuel economy for a model type using the vehicle-specific 5-cycle method, that method must be used to determine both the city and highway fuel economy.
(2) For 2011 and later model year automobiles, if the criteria in § 600.115-08 (a) are met for a model type, both the city and highway fuel economy must be determined using the vehicle-specific 5-cycle method. If the criteria in § 600.115-08 (b) are met for a model type, the city fuel economy may be determined using either method, but the highway fuel economy must be determined using the vehicle-specific 5-cycle method (or modified 5-cycle method as allowed under §600.114-08(b)(2) ).
(3) If the criteria in § 600.115-08 are not met for a model type, the city and highway label values must be determined by using the same method, either the derived 5-cycle or vehicle-specific 5-cycle.
(e) Fuel economy values and other information for advanced technology vehicles.
(1) The Administrator may prescribe an alternative method of determining the city and highway model type fuel economy values for general, unique or specific fuel economy labels other than those set forth in this subpart C for advanced technology vehicles including, but not limited to battery electric vehicles, fuel cell vehicles, plug-in hybrid electric vehicles and vehicles equipped with hydrogen internal combustion engines.
(2) For advanced technology vehicles, the Administrator may prescribe special methods for calculating and/or determining information other than fuel economy that is required to be displayed on fuel economy labels as specified in section 600.307-08 (k) of this part. For example, the Administrator may prescribe methods to determine the city and highway electrical energy consumption values and the all electric driving range for battery electric vehicles and plug-in hybrid electric vehicles.
(f) Sample calculations. An example of the calculation required in this subpart is in Appendix III of this part.

40 C.F.R. §600.210-08

71 FR 77946, 12/27/2006, as amended at 74 FR 61551, 11/25/2009; 76 FR 39554, 7/6/2011