I have a Supercrew XLT 4x4 with 5.4L and 3.55 gears with a K&N drop in filter, and I get 14-14.5 mpg in mixed driving conditions and on Thanksgiving weekend got 17.5 mpg on a highway trip to Starkville to watch Mississippi State beat Ole Miss. My commute to work is 17 miles one way in mixed driving, so I don't have any in-town stop-and-go data. I think the worst that I've gotten was 13.5 mpg. I have 3600 miles on the truck so far.

 

4x4 lariat supercrew, I get ~17.5-18 on the freeway and average around 15-16 per tank with the city driving thrown in. I have gotten as high as 20.4 on a vegas trip.

 

12.8 (summer with A/C) and 13.5 winter.
05 4x4 screw 3.73
31" stock LT tires.
17k on the clock.