I haul a 15K lb travel trailer and this truck has never let me down. I usually get 19-22 MPG on hwy, unloaded, and get 13-14 when towing, as long as I keep it under 70mph. If I go over 70, it drops to 10-11 and according to specs, 15K lbs is overloaded for 3/4 ton Dodge w/cummins. You must have nerf bars as the truck sits kinda high and is difficult to get into w/o side bars.
Cummins POWER and sits high, good mpg's no warranty issues
Improve cupholders, they bounce drinks around and spill.