Like the title says, I have heard many different things from manufacturer web sites to mythbusters saying that tonneau covers will help, or wont help, gas mileage. When they claim 10% better on a web site, that makes me think that something fishy is going on, I am sure some of you agree with both. All I really know is that tonneau covers help protect the bed and whatever is inside of it from the elements(well if its a sealed cover
). Any thoughts?