Consistently 15-16mpg in town, 13-14 off road (even with a lot of low range usage). As high as 18mpg highway if I'm going slow enough, as low as 13 highway if everything is working against me and I'm going really fast.
My JK is tall and heavy. But having a manual trans is probably a big help over the crappy auto that came with the weaker 3.8.
Initially I was corcerned about just running the white rim trail, but got back to town with over half a tank left. Range hasn't been much of an issue as long as I'm using my brain.