Comparing gas mileage with your old truck and your new one is about the same as comparing apples to oranges, the new half ton trucks of any make are considerably lighter, shorter height and narrower. If it was a 2500 even 2wd you'd be in the mid to low teens for gas mileage, the same either way with a new Ford..... Not trying to knock on your truck but just being realistic.

 

Good point twigs....guess I'm a bit behind the times! (I'm old enough to remember the 460's getting something like 6 miles to the gallon....empty or full)

 

Hell I get 13.5 with my truck. Glad I don't drive it much.