F350,Crew cab,dually,4x4,4.10 gears, automatic:
I do not see how you hope to get great mileage with this combination.
F250, std cab, 2wd, 3.55 gears, srw, and manual transmission is going to give you the best mpg.
That being said, we did 21 mpg at 55-60 mph empty.
We still average...