I have not reset mine in 5 tankfulls and I am sitting on 18.2 MPG. I would guess that it is 85% highway at 70MPH. I have found that if I go 80MPH and drive more in the city or start-stop driving that I will average about 16.5. I also get about 1MPG better in the summer for some reason.

04 Scab 5.4L Lariet 2WD 3.73 rear 31" tires

 

Summer gas is better than winter gas. Refineries change the blend for winter.

Grim

 

04 Reg Cab XLT 4x4 short box, 5.4 with 3.55 rearend. Winter in the snow in FWD 13-16, summer 16-17, HWY 20+.

 

I have an 01 with the 5.4 and I'm averaging 16 mpg city and 20 mpg on the highway. I do a lot of stop n go in San Antonio so...I think it's damn good....I have 3.55 gears, K&N, E fans and the hypertech so...I'm sure that helps.....I'm hoping to get more performance out of the Xcal2 when it gets in....I'll let yall know....hope this helps someone! Oh yeah, I also dropped it 3" front and 4" rear....I'm sure that makes a difference aswell.....

 

Old truck : 05 Screw 4x4 3.73 Lifted on 35"s 10.5-11MPG City 12.5MPG HWY

New Truck: 05 Screw 4x4 3.73 (Stock wheels/no lift) 15-16MPG City 16.6-17.5MPG HWY