Aerostealth, I think you may be onto something. I've had a topper on my truck for 5 years now, and took it off earlier this month thinking we'd see better mileage. A 1,000 trip to IL and back says nadda, at least at a glance. Seems to be the same. Haven't crunched the numbers yet, but the only think that was obvious was less weight going up hills. I freely admit the truck looks better with the topper installed.
