Gas mileage on an F-250

The average on Fuelly is like 15.5 for that truck. Seems unlikely. However, I have seen a duramax with an efi tune get 27 mpg when I was riding in it. Talk about having no power though...

 

It's doable. the gas mileage on the new psd's are all over the place, you can find people getting anywhere from 13-24mpgs depending on driving habits and location. Just like a select few people on this board are getting mid to upper 20's in their 4wd tacos, while others are getting 15. Pops has a 2011 fx4 crew cab psd, it's averaging 18 and change in mixed city hwy and mtn driving. He said it seems to be improving slightly over time as well.

I'm right down the road from Garmon's diesel, my brother was one of his groupies for a few years. he (brother) had two 6.0 psd's CC 2wd's that were consistent 23mpg hwy if he could keep his foot out of it, i think his last one was 450ish at the wheels. Big tires don't affect a diesel like they do gassers either. Garmon can do some crazy shit to a diesel, especially the older Cummins, 625hp is nothing. In fact last i saw him he has a two wheel drive standard cab truck that was in the area of 7-800ish at the wheels, i believe he said it would get high 20's - no bs.