Fill out your sig so we know what kind of specs the truck has. Is it a dually, SRW, 3.54s, 4.10s, 4x4, 4x2?
With that said, I used to own a 1996 OBS 7.3 Single cab longbed F-250, and that thing sucked the fuel with 4.10s. I averaged 16, but would get as low as 11 in town.
Sounds a little low to me, but , you are not the first person I have heard complaining about 12. Unless you are the same guy all over the web complaining about it.:lolly:
My 00 F-350 4x4 reg cab duelly 6-speed with 4.10's has superchips 120hp programer and a straight pipe and I'm lucky if I get 12 outta it. Its all good though cause its just a work truck.
It got about 10 with out the programmer or straight pipe.