Code of Federal Regulations Title 40. Protection of Environment 40 CFR Pt. 600, App. II—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 MPG_c, for the vehicle may be calculated by substituting the HC, CO, and CO₂ grams/mile values into the following equation.

MPG_c=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 MPG_h of 36.9. According to the procedure in § 600.113, the combined fuel economy (called MPG_c/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 MPG_c, 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:

MPG_c = (5174 x 10⁴ x CWF x SG) / [((CWF x HC) + (0.429 x CO + (0.273 x CO₂)) ((0.6 x SG x NHV) + 5471)]

Example:

MPG_c = (5174 x 10⁴ x 0.868 x 0.745) / [(0.868 x .139 + 0.429 x 1.59 + 0.273 x 317)(0.6 x 0.745 x 18478 + 5471)]

MPG_c = 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 MPG_h of 36.9. According to the procedure in § 600.210–08(c) or § 600.210–12(c), the combined fuel economy (called MPG_comb) for the vehicle may be calculated by substituting the city and highway fuel economy values into the following equation: