CAFE has two problems. The first, as you've mentioned, is the suspect bifurcation of the standards between regular cars and "light trucks". The second problem

CAFE has two problems. The first, as you've mentioned, is the suspect bifurcation of the standards between regular cars and "light trucks". The second problem is that the footprint-based formulas used within a category do not reflect the practical utility of the vehicles and let larger cars off easier. A high-roof compact car like the Honda Fit can comfortably carry 5 people and opens up quite well for transporting a lot of stuff. Because it's small and light, it gets great gas mileage especially on the highway. Yet it's penalized by CAFE because it has a small footprint and so is expected to get unrealistically high fuel economy. Whereas, a larger sedan like the Honda Civic can also carry 5 people (with some more amenities) but has a paltry trunk that can't be used to transport much more than grocery bags. Even as a hatchback, the roof is a lot lower than in the Fit, so it can transport larger items like furniture, but only if they're flat. Yet it scores better on CAFE because its larger footprint allows it to have more realistic fuel economy.