the Z06 corvette with 550 hp still gets better gas mileage than a suv with a v8. (no gas guzzler tax) aerodynamics play a huge role in a cars fuel mileage. the gov is fucking dreaming if they think every car/truck/suv can get 54. ain't going to happen going downhill and with the wind. even toyota was sued by a lady over their fuel mileage claims on her hybrid. it only gets about 28mpg or something like that.