I had a 3.7 Commander, if it had been a 4.7 I'd probably still have it. The best I could do for mileage was 22mpg at between 50-55mph but most of the time it was more like 18-19 at that speed. The problem was pushin it on the highway, anywhere from 14-17mpg at 70-80 mph but mostly 16.5 mpg at 75mph. I also own a 99 WJ with a 4.7 which gets about 1 mpg better than the Commander did. I traded in the Commander for a diesel WK, up here diesel is $3.06 and $3.55 for gas per U.S. gallon.