Final average on our trip to Dallas was just over 15. Seldon went over 60 mph, had some traffic, ran the a/c more than 1/2 the time and had ethanol in most of the gas . I found that using the cruise control causes the trans to shift down too easily and affects mileage too. The ECT button didn't seem to make any diff in when it shifted. I suppose that without air, ethanol and heavy traffic, I'm sure I could get 17.
Tone/Joan