I get 55 mpg downhill in Colorado. My average over 10 years of towing with various diesel pickups has been 9-10. Right now I have Duramax with a Edge, turned up about 60 hp and I get around 10.3 in cool weather and with AC and hot weather 9.6 last trip to OK and back to Va but pushed going west due to a death. I think it depends on fuel also because some I get good and some bad. My pickup will avg 17 1 mo, the next 13. Anyone who brags he can get better than 10 can hook on my Arctic Fox 31W and tow it to Pittsburgh and back and if he does I'll buy the fuel. No one ever came to take me up on it yet.