Originally Posted by HoustonHemi
I do remember hearing about M-busters finding out that dropping your tailgate didn't help your MPG,,,, I didn't see the actual episode, though,,,
Did they do any testing in regards to tonno's?
I believe bed length does dictate tonno effectiveness,,, I can see where an 8 ft'er would 'scoop' more than a 5 ft'er,,,
(Yeah, I know it's 'tonneau', but 'tonno' is easier for me to type! )
I think the first time they tested the fuel mileage with the tailgate up vs tailgate down, they were using (in Dodge lingo) Crew cab trucks with a short bed. When they revisited it, it looks like they used a standard (short) cab and a longer bed. They did test one of the hard fiberglass tonneau covers when they revisited it, but their result was that tailgate mesh beat tailgate up, tailgate down, and the tonneau cover for efficiency.
They didn't test the different methods on different length beds, but I'm still pretty sure that the length and width of the bed makes a difference.