It's an old wives' tale that pickup truck owners can get better gas mileage by lowering the tailgate. Remember the SCCA truck racing series in the late '80s and early '90s? The Archer Brothers team conducted numerous tests with their Jeep Commanches and never found extra speed or better fuel economy.
There have been wind-tunnel tests that show tonneau covers can improve aerodynamic flow and reduce drag. But no one in recent memory had ever attempted a real-world test of a tonneau cover's ability to improve fuel economy.
Now Snugtop, a company that makes tonneau covers and bedcaps for pickups, has an answer. The company conducted a very intensive test this month at Irwindale Raceway in Southern California. Using fullsize pickups from Dodge, Ford and Chevy, the trucks were driven 100 laps at 45 mph. Two had tonneau covers and the third had a bedcap. The gas tanks were topped off and the tonneaus and bedcap removed for another 100 laps at 45 mph. Bottom line: Snugtop reports a 1.3 mpg improvement and says even better mileage can be expected at higher speeds.