I have 2012 Sport Unlimited. 6 speed with 3.21 gears. The dealer had a leveling kit and 35/12.5r18 nitto trail grapplers put on. The dealer here does that to a lit of the new jeeps to help sale them I suppose. I don't have any power problems like a lot of people say you will have with 3.21, but then again I traded an H2 Hummer for the Jeep. I also haven't driven another jeep other than the '97 wrangler with 5 speed and 4 banger so...Anyway, I haven't been on the interstate but a couple of times getting16-17 and 12-13 in town.