I have a 2018 F350 6.7 diesel, with the 4:10 gears w/ electric lockers front and back. I put in 51 gal drag up tank w/ tool box, with aitlift air bags; b&w companion hitch, and new tires for off toad and I pull 16k 40’ 5er. In town running round I generally get about 11-13! On Highway it’s was dueing 18, but pullin trailer my trailer up hill 4-9, down hill, just use your imagination! Wouldn’t take for my truck!!!I've been getting a steady 15 mpg around town and 16 to 17 mpg hwy depending on speed. 4.10 gearing keeps me at 70 mph max on the hwy. Towing our close to 17K pound 5th wheel I usually get 9 mpg @65 mph. Not bad for a DRW with the 4.10's.