Mileage while towing my 14' gooseneck horse trailer has always been around 11.5-11.8 mpg on the hiway at 70-75 mph with tthis truck -:t . I had the computer reflashed a couple of months ago, I "swiss-cheesed" my airbox, and I unplugged my egr valve. I finally got to tow with this set up. On my way to the rodeo into a major headwind I managed 12.6 mpg. On my way back home yesterday in perfect weather I got 14 mpg . If I can keep that up I will be in hawg heaven. This is even bettewr than my lly would get. hope it keeps up.