Well, assuming you have a short bed, it would be 26 gallons. I personally get about 14-16 mpg just running around base and a trip or 2 to fairbanks (about 30miles one way). On the highway, I can get 400 miles pretty easily out of a tank of fuel. As far as your friends getting that kind of mileage, do they have long beds? I believe our long bed is 32 gallons and a ford's is 35. don't quote me on that, but I think that is what they are. Have you ever ridden with your friends and seen for yourself the mileage they are getting? I found out most people exaggerate or go by what their computer in the truck tells them. Rarely do they hand calculate the mileage. I can tell you for a fact, my truck gets better mileage than my friends 02 F350 with the 7.3L. Now that being said, I have seen almost 21 mpg on my truck unloaded with the stock tires..this was only once though. It also depends on driving styles and many other variables, but for the most part, everyone's claims of getting 20+ mpg is BS. You should be getting about 16-20mpg empty on the highway and probably 14-16 in town. When loaded, I know my mileage drops to about 12-14 depending on how heavy I am loaded.