Wind Resistance and Mileage

I don't know of anyway to calculate the trailer aerodynamics and the fuel economy. I would expect around 15 mpg if you don't drive too fast.

I thank you. This proves, to be another area, of buyer beware. In reference, to a different manufacturer and smaller SUV, the salesman, even, asked me, if I were really going, to tow. Though the vehicle had a good tow rating, of 5K Lb, he told me that it might tow 4K Lb but only, on the flats. The manufacturers give grand ratings but withhold the reality, of operation, at the rating. Being a mechanical engineer and I designed light/heavy duty mobile equipment, it would be interesting, to test and document vehicles, at rated loads. Especially, tow vehicles. Again, I thank you, for your input.

If you want a serious tow vehicle do your self a favor and get a pickup such as a F150 or F250. 99% percent of salesmen do not have a clue and the other 1% are full of poop. I have never seen anyone spec fuel economy with a load. There are too many variables to get a meaningful answer. Best bet is to try vehicle specific forums to see what other owners say.