How is a manufacturer’s CAFE determined for a given model year?
A manufacturer’s CAFE is the fleet wide average fuel economy. Separate CAFE calculations are made for up to three potential fleets: domestic passenger cars, imported passenger cars and light trucks. The averaging method used is referred to as a “harmonic mean”. The regulatory language describes the calculation as: “the number of passenger automobiles manufactured by the manufacturer in a model year; divided by the sum of the fractions obtained by dividing the number of passenger automobiles of each model manufactured by the manufacturer in that model year by the fuel economy measured for that model.” The numerical example below illustrates the process.
