Our new truck doesn't have a tonneau cover for the bed, and we're thinking that it would probably improve aerodynamic performance (and mileage) if it did. Does anyone have experience with adding one ...
I've had the high top cap, a regular cap flush with the roof, and a soft trifold tonneau. I didn't notice any change in MPG. Not saying there isn't any, but it would have to be really slight. I would decide on whether or not to buy one based on the way I use the truck. I doubt you'll see any noticeable difference. Not like the savings are going to pay it off in it's lifetime.