[Bullockracing]

I slowed from my usual 9 over the speed limit cruise to a 1 over the speed limit cruise. I didn't get a rash, so I'll keep doing it. My method was still 9 over the speed limit up to 45 mph (34 in a 25, 44 in a 35 etc). At 45, I change to 1 over, which keeps my average speed up into a more efficient range, without the larger drag from speeds over 45. This didn't work in my Mustang, but it did in the new ride...

I hypothesize that the larger engine in the Mustang was not affected by the relatively small differences in drag. At cruise rpms, the motor probably had more than enough torque to push the car, so variances between 55 and 70 had little to no effect, since long cruises never generated significant changes in FE.

In a larger (wetted area) car with a smaller engine, such as the Fusion, the difference is greater.