As someone has already mentioned, fuel mileage is very subjective. Our truck/camper combo with the speed and how I drive returns 16 US mpg all day long. We towed a 26' Dutchman TT a few years back, mileage was less at 12 US mpg but we were carrying more stuff in our truck bed and in the trailer. GVW with camper on commercial scales is right at 12,000 lbs, GCW of truck and trailer was right around 14,500 lbs. No shortage of power either way but our truck with camper is more fuel efficient.