I am attempting to purchase a 2003 F350 7.3 4x4 crew cab, and the computer is only showing 11mpg no matter how easy I drive it. Is this normal?? It does have 3 in block in the back leaf springs, and is running 305 70 R16's, which is slightly bigger, but should this really effect it that much?? Thanks guys, Matthew

 

First off, never trust the computer. My 2000 F350 has shown me 24.5 mpg before when I was actually getting about 16.5-17 mpg which for a 4x4 Crew Cab auto with 3.73s isn't that bad. And have you tried reseting the mileage calculator by pushing both the buttons at the same time while on the MPG reading? If you haven't, then it is figuring average since it was last reset. If there are a few thousand miles on it since the last reset, it takes longer for it to change especially if the truck was pulling or hauling something heavy and dropping the mileage. With my 28' gooseneck I average 11-12 mpg. Miss my 97 standard cab that would pull the same trailer and get 17mpg.