Originally Posted by maddyfish
Some cars don't even get best mileage at 55. According to my wifes' cars gas mileage display it gets best mileage at about 64mph on flat ground.
Eh... Could be, but usually cars aren't geared that badly. Did you do several alternating bi-directional runs over the same loop within a short amount of time (weather) and CC set at those respective speeds? Make sure the torque converter was locked up in both cases? Etc... For the vast majority of cars, as long as conditions are the same,
slower in top gear is better.