I've got a 3.0 and I average around 17.5 city and 21-22 highway. I've noticed that my mileage actually seems to be worse if I try to be extra easy on the pedal away from a stop. If I accelerate reasonably and get to the speed I want to maintain lets say 55 within around 10 seconds (guessing) I seem to get my best mileage. I'm sure it has to have something to do with time spent accelerating and consumption not being linear to throttle application.