Well the tiltle pretty much sums it up. Cap or tonneau, which provides better gas mileage? I've found some info that says a tonneau cover will help gas mleage, but what about a cap? Would a bed cap help mileage? How would it compare to a tonneau?
Welcome to FTE rasford. Unless you do all highway driving, I think the gains will be negligible. I have run a tonneau in the past, and thought it made the truck roll easier (think of the bed like a big scoop, constantly holding you back). Did it effect mileage? I dont think so. Also, I would go with a tonneau just for the sheer convenience factor. It would be a pain for me to have to take the top on and off when I wanted to move something large, like my four wheeler, or a fridge.
I purchased a K-Cover folding cap for my screw. It is a solid hard cover made from aluminum that fold in half or can completely be removed in less than 3 minutes. Very nice product..oh..I get about 1.5 more mpg..