I always said that the Hurst had the aerodynamics of a WalMart. I also know that if I try to pedal the dually with the trailer on behind anything over 65, the mileage drops quick!!! As for todays car, I ran my Montego to Michagan last fall running 75 mph both ways. With the running around and everything that was done-- round trip was 28.5. Recently, I ran the car on a 90 mile jog setting the cruise at 65-- 30 mpg. Difference, yes--- enough of a difference-- no.