These threads are usually full of BS but this one looks pretty honest so far. My 05 automatic 4WD gets above 20MPG empty and recently did 12MPG pulling a 24 ft enclosed down to Seattle and back. The mileage seemed the same with the trailer loaded or empty, the enclosed buck a lot of wind. I do better pulling an open trailer but can't remember how well now, I think something like 15-17MPG with a loaded open trailer.

Sheldon