Just put 450 miles on the truck today and calculated my mpg.
@ 64 mph, I was getting 16.1 mpg (drove 120 miles at this speed)
@ 69 mph, I was getting 15.4 mpg. (drove 135 miles at this speed)
@ 82 mph towing a 17' Boston Whaler (approx 3000lbs total) I was getting 10.5 mpg (drove 190 miles at this speed)
Truck has a 2.5" lift with 35x12.50x18's. Truck is completely stock except for an intake system. DP back 4" exhaust dpf/cat delete and Spartan will be in Tuesday. Hopefully this will help a little.