Here's my recent experience with aerodynamics and mpg. On the way to Everybus in April I had my 12x12 EasyUp strapped to the roof of the Westy, along with 2 folding chairs. I was traveling down I-81 in Virginia. I admit, too, that I was pushing it pretty hard, running 70-75 mph most of the way. My fuel mileage was shocking-around 10mpg. At first I thought my fuel gauge was acting up, but fill ups showed it was as empty as the gauge said it was. Last Friday, on the way to Natural Bus, I put the EasyUp in the camper along with the chairs, had nothing on the roof. Same route, down I-81, just not as far. I also did my best to keep my speed between 55-60 mph. My mileage jumped to around 16.5. Don't know which contributed the most to the increase, the lower speeds or not having the crap on the roof, but that's the way I'm traveling from now on at $4.00+ per gallon gas.      Jeff