CFR > Title 40 - Protection of Environment > CHAPTER I—ENVIRONMENTAL PROTECTION AGENCY > SUBCHAPTER Q—ENERGY POLICY (Parts 600–611) > PART 600—FUEL ECONOMY AND CARBON-RELATED EXHAUST EMISSIONS OF MOTOR VEHICLES > SUBPART B—Fuel Economy Regulations for 1978 and Later Model Year Automobiles—Test Procedures (§600.101-08 to §600.115-08) > 600.113-78—Fuel economy calculations.

600.113-78—Fuel economy calculations.

The calculations of vehicle fuel economy values require the weighted grams/mile values for HC, CO, and CO2 for the city fuel economy test and the grams/mile values for HC, CO, and CO2 for the highway fuel economy test. The city and highway fuel economy values must be calculated by the procedures of this section. A sample calculation appears in appendix II to this part.
(a) Calculate the weighted grams/mile values for the city fuel economy test for HC, CO, and CO2 as specified in § 86.144 of this chapter.
(b) (1) Calculate the mass values for the highway fuel economy test for HC, CO, and CO2 as specified in paragraph (b) of § 86.144 of this chapter.
(2) Calculate the grams/mile values for the highway test for HC, CO, and CO2 by dividing the mass values obtained in (b)(1) by the actual distance traveled, measured in miles, as specified in paragraph (h) of § 86.135 of this chapter.
(c) Calculate the city fuel economy and highway fuel economy from grams/mile values for HC, CO, and CO2. The emission values (obtained per paragraph (a) or (b) as applicable) used in each calculation of this section shall be rounded in accordance with § 86.079-26(a)(6)(ii). The CO2 values (obtained per paragraph (a) or (b) of this section as applicable) used in each calculation in this section are rounded to the nearest gram/mile.
(d) For gasoline-fueled automobiles, calculate the fuel economy in miles per gallon of gasoline by dividing 2421 by the sum of three terms:
(1) 0.866 multiplied by HC (in grams/miles as obtained in paragraph (c)),
(2) 0.429 multiplied by CO (in grams/miles as obtained in paragraph (c), and
(3) 0.273 multiplied by CO2 (in grams/mile as obtained in paragraph (c) of this section).
Round to quotient to the nearest 0.1 mile per gallon.
(e) For diesel powered automobiles, calculate the fuel economy in miles per gallon of diesel fuel by dividing 2778 by the sum of three terms:
(1) 0.866 multiplied by HC (in grams/mile as obtained in paragraph (c) of this section),
(2) 0.429 multiplied by CO (in grams/mile as obtained in paragraph (c)), and
(3) 0.273 multiplied by CO2 (in grams/mile as obtained in paragraph (c)).
Round the quotient to the nearest 0.1 mile per gallon.

Code of Federal Regulations

[42 FR 45657, Sept. 12, 1977, as amended at 43 FR 52929, Nov. 14, 1978]
The calculations of vehicle fuel economy values require the weighted grams/mile values for HC, CO, and CO2 for the city fuel economy test and the grams/mile values for HC, CO, and CO2 for the highway fuel economy test. The city and highway fuel economy values must be calculated by the procedures of this section. A sample calculation appears in appendix II to this part.
(a) Calculate the weighted grams/mile values for the city fuel economy test for HC, CO, and CO2 as specified in § 86.144 of this chapter.
(b) (1) Calculate the mass values for the highway fuel economy test for HC, CO, and CO2 as specified in paragraph (b) of § 86.144 of this chapter.
(2) Calculate the grams/mile values for the highway test for HC, CO, and CO2 by dividing the mass values obtained in (b)(1) by the actual distance traveled, measured in miles, as specified in paragraph (h) of § 86.135 of this chapter.
(c) Calculate the city fuel economy and highway fuel economy from grams/mile values for HC, CO, and CO2. The emission values (obtained per paragraph (a) or (b) as applicable) used in each calculation of this section shall be rounded in accordance with § 86.079-26(a)(6)(ii). The CO2 values (obtained per paragraph (a) or (b) of this section as applicable) used in each calculation in this section are rounded to the nearest gram/mile.
(d) For gasoline-fueled automobiles, calculate the fuel economy in miles per gallon of gasoline by dividing 2421 by the sum of three terms:
(1) 0.866 multiplied by HC (in grams/miles as obtained in paragraph (c)),
(2) 0.429 multiplied by CO (in grams/miles as obtained in paragraph (c), and
(3) 0.273 multiplied by CO2 (in grams/mile as obtained in paragraph (c) of this section).
Round to quotient to the nearest 0.1 mile per gallon.
(e) For diesel powered automobiles, calculate the fuel economy in miles per gallon of diesel fuel by dividing 2778 by the sum of three terms:
(1) 0.866 multiplied by HC (in grams/mile as obtained in paragraph (c) of this section),
(2) 0.429 multiplied by CO (in grams/mile as obtained in paragraph (c)), and
(3) 0.273 multiplied by CO2 (in grams/mile as obtained in paragraph (c)).
Round the quotient to the nearest 0.1 mile per gallon.

Code of Federal Regulations

[42 FR 45657, Sept. 12, 1977, as amended at 43 FR 52929, Nov. 14, 1978]