If you can stick to 70 and under, you can pull down an easy 18MPG with easy shifting and not racing the truck. I just figured my mileage tonight. 36 gallons of fule, for 688 miles and I got 19. 1MPG. That is pretty good for a truck this size. I realize an auto has beeter overdrive gearing, but you still need to rev it higher in order for it to ****, and that wastes fuel. But man, the truck is right in its sweet spot at 60-70 (Cummins recommended sweet spot) and the truck just flat out never needs to come outta 6th gear. Scotty