01 4.0L Auto with 4.10's and 35's.. Intake, TBS and flow super 40 dumped... Right around 16 on average

 

4.0 4x4 auto 4dr w/ 3.73s, 3in BL and 33s, last tank was the best to date at 18 mpg all on the highway.

The drop in K&N helped around 1/2 a mpg, but I haul around 2-300 lbs of gear all the time.

I'm also a little over 1000ft elevation, when I was up around 7200ft, with a stock truck (and maybe a couple dirty sensors) my worst was 10.5 mpg.

 

31's with a 3 inch spindle lift

1998 2.5L 4 banger

20-21 city/ 25+ highway.