We've got a 21 F250 w/ the 7.3 and it's been fantastic. More than enough power for our needs, reliable but yes, thirsty. We average anywhere between 9.6 to 10.4. That's w/ a Carli 2.5" lift and 37's, vertical bike rack in the hitch usually w/ 3 MTB's. Right around 50,000 miles right now.