I remember when Snugtop did this test. I am confused as to how the cap got switched to the Dodge, which actually had a tonneau cover on it and showed the best mileage gains of the three trucks.
Snugtop Fuel Economy Test Results - Chevy, Ford & Dodge Comparison - Sport Truck Magazine
The Chevy had the cap on it and showed a decent .5 mile per gallon increase.
I guess I am confused as to why Snug top would switch the trucks in the text describing the test on their web page? Maybe they have run another test since the one I provide two links to. You can clearly see the Chevy having the cap on it, at least in this test it does.
Just fighting em fair,
Bondo