Start using "power" button ! I am not kidding. I saw increase in milage after I've read on the board about "power" button. Check tire preassure, air filter, gas filter, PVC valve...... What grade gas do you use ? I use mid-grade Mobile only from day one and it seems to give me fair milage in the city.
People report better milage with better fluids also (transfer case, diffs, gearbox etc...) I plan to swap fluids to either Royal Purple or Mobile 1.

Good luck !