Of course gas mileage depends a good bit on driving habits. Based on your 15 mpg estimate, I'm guessing it's an automatic transmission. If so, 15 mpg is normal for city driving. The EPA estimate is 15-17 for the automatic, 17-20 for the manual. If you have the manual transmission, there is either something wrong or you drive like a maniac (or your estimate is wrong) <img src="/forums/images/graemlins/smile.gif" alt="" /> . it would be a good idea to check everything included in normal scheduled maintenance list like all fluids, filters, etc. Even though it may run like a new one, it's not, and who knows what has been done to it or where it's been. Chrysler says change the fluid and filter in automatic transmissions regularly, I have a service manual for your Jeep around here if you want details but unless you have solid documentation that proper maintenance has been done, you should do it. I would change the oil in EVERYTHING if it were mine. And be sure to use the right fluids when you refill. Proper air pressure in tires can help with mileage also. Check it if you haven't. I think you can fit 31 or 32 inch tires with a 2" budget boost lift. Check into them. don't expect larger tires to help with MPG though. Again, a lot depends on how you drive, running 32" tires on my CJ didn't hurt my mileage a bit (stock 3.31 gears, man. trans.) I drive like the old Grandpa I am though. Your results may vary! <img src="/forums/images/graemlins/lol.gif" alt="" />