I generally lock in the cruise control at 4 or 5 over. I'm seldom in a hurry, but when I am, I usually don't use the cruise control. Last year I was testing E85 mileage, as well as standard mid-grade ethanol, regular non ethanol and premium. My mileage for ethanol blend was 10% less than regular. E85 was 20% less than regular. The premium tank got lower mileage than the Ethanol blend, so I don't trust the results of that test. Anyway, as I continued testing and reporting the results on message boards, I got told how speed affects mileage. So I tested at a slower speed and was surprised how mileage would go up. I never noticed that before. It does have the effect that I tend to drive at more moderate speeds.