# 40 CFR Appendix II to Part 600, Sample Fuel Economy Calculations

Appendix II to Part 600 - Sample Fuel Economy Calculations

(a) This sample fuel economy calculation is applicable to 1978 through 1987 model year automobiles.

(1) Assume that a gasoline-fueled vehicle was tested by the Federal Emission Test Procedure and the following results were calculated:

HC = .139 grams/mile
CO = 1.59 grams/mile
CO2 = 317 grams/mile

According to the procedure in § 600.113-78, the city fuel economy or MPGc, for the vehicle may be calculated by substituting the HC, CO, and CO2 grams/mile values into the following equation.

MPGc = 27.7

(2) Assume that the same vehicle was tested by the Federal Highway Fuel Economy Test Procedure and calculation similar to that shown in paragraph (a) by this appendix resulted in a highway fuel economy or MPGh of 36.9. According to the procedure in § 600.113, the combined fuel economy (called MPGc/h) for the vehicle may be calculated by substituting the city and highway fuel economy values into the following equation:

(b) This sample fuel economy calculation is applicable to 1988 and later model year automobiles.

(1) Assume that a gasoline-fueled vehicle was tested by the Federal Emission Test Procedure and the following results were calculated:

HC = .139 grams/mile.
CO = 1.59 grams/mile.
CO2 = 317 grams/mile.

(2) Assume that the test fuel used for this test had the following properties:

SG = 0.745.
CWF = 0.868.
NHV = 18,478 Btu/lb.

(3) According to the procedure in § 600.113-08, the city fuel economy or MPGc, for the vehicle may be calculated by substituting the HC, CO, and CO2 gram/mile values and the SG, CWF, and NHV values into the following equation:

MPGc = (5174 × 10 4 × CWF × SG) / [((CWF × HC) (0.429 × CO (0.273 × CO2)) ((0.6 × SG × NHV) 5471)]

Example:

MPGc = (5174 × 10 4 × 0.868 × 0.745) / [(0.868 × .139 0.429 × 1.59 0.273 × 317)(0.6 × 0.745 × 18478 5471)]
MPGc = 27.9

(4) Assume that the same vehicle was tested by the Federal Highway Fuel Economy Test Procedure and a calculation similar to that shown in (b)(3) of this section resulted in a highway fuel economy of MPGh of 36.9. According to the procedure in § 600.210-08(c) or § 600.210-12(c), the combined fuel economy (called MPGcomb) for the vehicle may be calculated by substituting the city and highway fuel economy values into the following equation:

[ 51 FR 37852, Oct. 24, 1986, as amended at 71 FR 77958, Dec. 27, 2006; 76 FR 39570, July 6, 2011]

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