Now it's much more complicated. There is a sliding scale based on the footprint of each individual vehicle. The footprint is defined as the wheelbase times the average of the track width or the area within the wheels. The larger the footprint, the lower the threshold that vehicle has to meet. Therefore for two cars of similar overall size but one with a longer wheelbase, the longer one would have a lower mileage requirement. Each automaker is then assigned an individual threshold to meet based on the sales weighted average footprint of the vehicles it sells. A company that sells more large footprint vehicles would have a lower hurdle to jump. One that sells predominantly smaller cars would have to get better mileage. As a result a company like Porsche or Ferrari who sell relatively small sports cars would have to meet a higher standard than Ford or General Motors who sell more large trucks. The entire premise of this rule is absurd. This rule will likely have the effect of giving manufacturers an incentive to maximize the wheelbase and track of new vehicles in order to minimize their CAFE requirement.
The only saving grace here is that, overall, as fuel prices continue to climb, buyers are likely to migrate to more efficient vehicles regardless of the footprint.
[Source: NHTSA, AutoWeek]