This is my 2011 Wrangler Unlimited getting 30 mpg (with 165K miles on the odo!) with 3.8l V6, 6 speed transmission, 2.73:1 gears (I really want to put 4.56s in it). Here's how it works: the MPG indicator calculates average (not momentary) fuel usage based on fuel flow and speed. I reset it while driving at about 35-40 mph on a paved backroad, because other wise what I had been doing earlier (which was driving through mudholes down by the river, btw) would affect the reported mpg. For awhile I kept it above 50 mpg and even well into the 70s (average remember; not momentary. That is significant) and then settled down to 48 mpg. But then I had to go uphill for a bit, stop and wait for traffic, and accelerate to 50+ mph on the highway. That brought the overall average down to 30 mpg.
It's all about how you drive it. Well, that and not putting 37" Super Swampers and a rack of 8" off-road lights on it.