Combined fuel economy
Combined fuel economy means:
(1) The fuel economy value determined for a vehicle (or vehicles) by harmonically averaging the city and highway fuel economy values, weighted 0.55 and 0.45, respectively.
(2) For electric vehicles, for the purpose of calculating average fuel economy pursuant to the provisions of part 600, subpart F, the term means the equivalent petroleum-based fuel economy value as determined by the calculation procedure promulgated by the Secretary of Energy. For the purpose of labeling pursuant to the provisions of part 600, subpart D, the term means the fuel economy value as determined by the procedures specified in § 600.116-12.
40 CFR § 600.002
The following definitions apply throughout this part: