As you may be aware, CAFE mileage statistics aren't actually representative of what a given manufacturer is likely to achieve, as they are adjusted for all sorts of reasons. Therefore, Cars.com chose to go by the EPA's mileage ratings to calculate its figures. For the same reason, the impending fuel mileage requirements being proposed by the Feds aren't quite as harsh as they might seem. For instance, CAFE's 2007 rating for Honda's domestic passenger-car fleet comes in at 33.5 mpg, while Cars.com estimates a much more realistic 24.9 mpg. So, the EPA's estimations are still useful for comparing individual car models, and Cars.com's TMI rating is useful for comparing the manufacturers themselves. Remember, though... your mileage may vary.