Quoted:
. I have all ways heard
Well, despite what you have HEARD, I get 15-16 or so mixed driving, with the F250, CC,8' bed, 4X4 w/3.73s and auto.
Have cracked 18, highway,IF I can keep it at or below 2000rpm (seems to be the sweet spot)
The F350 is IDENTICAL, but with a high, heavy steel cap and boxes, loaded with tools, so easily 1200-1500 lbs heavier, and yet consistently has gotten better mileage since new!
And since it's my work truck, I usually have my foot in it a good bit deeper! (maybe that's the secret?) Have hit a hair over 19 mpg on long road trips, loaded.
Mileage on both drops during winter.
My brother's '99 (same setup, but 7.3 and Xcab) gets 19+ on road trips, and it's knocking on 300,000 and pulls 5-12K almost every day!
Also has a 12V Cummins in a Dodge 3/4 ton that he thinks highly of.
Want to talk about bad mileage? Have a '11 F450 with 6.7 and 4.30s, in a 10' dump, dually 4X4.
It does, however, scoot, considering how much it weighs