The Administrator shall measure fuel economy for each model and calculate average fuel economy for a manufacturer under testing and calculation procedures prescribed by the Administrator. However, except under
section 32908 of this title, the Administrator shall use the same procedures for passenger automobiles the Administrator used for model year 1975 (weighted 55 percent urban cycle and 45 percent highway cycle), or procedures that give comparable results. A measurement of fuel economy or a calculation of average fuel economy (except under section 32908) shall be rounded off to the nearest .1 of a mile a gallon. The Administrator shall decide on the quantity of other fuel that is equivalent to one gallon of gasoline. To the extent practicable, fuel economy tests shall be carried out with emissions tests under section 206 of the Clean Air Act (
42 U.S.C. 7525).