Ah, the real challenge-- Making this 318 V8 (5.2L) average at least something different. For such a small V8, it sure gets miserable fuel economy, on average 13-14 mpg. Currently a project to flip and sell, but more and more loving it's comfort and off-road abilities (yes, I do. Made good use of the skid plate today in fact), I decided to start messing with a grille block. 6 of the 8 openings for the Jeep were closed, lower grille still open. Stayed cool in all traffic in today's lovely 75 degree weather, just a hair warmer.
The results? On the flattest piece of highway I can find in Austin, +4-5 mpg at 65 mph on average (23-24 mpg), and +2-3 at 75 mph (20 mpg). And interestingly enough, 2 mpg while climbing the hills. This thing is dead on consistent to average 12 mpg at 65 or so mph running uphill on the way home. Grille block in place, 14 mpg.
Biggest problem is that it's full time 4wd, it's always powering the front axle. And you can't pull the front driveshaft with out ruining the center diff in the transfercase.