Does a tonneau cover effect fuel economy?

According to this article it does. In short, it gives you a free gallon of gas for every twenty you use. From Auto Trim & Restyling News – August 2001 From “Tailgate Talk -Does Removing A Tailgate Effect Fuel Economy?” By Bruce W. Smith According to many experts, the best way to improve a pickup’s fuel economy is to leave the tailgate up and cover the bed with a quality aftermarket Tonneau cover. “Tonneau covers on pickup boxes reduce aerodynamic drag,” said Ford’s Jack Williams. “We’ve seen reductions of about 8 to 10 percent on the F150, which means the average fuel economy improvements for EPA city/highway cycle [test] is about 2 percent. “The average steady-state [cruise control] fuel economy improvement at highway speeds is closer to 5 percent.” Adding a tonneau could mean an improvement in fuel mileage that is the equivalent of a free gallon of gas for every 20 gallons used.