Fuel Economy was tested on the Mustang dyno using the OBD-II fuel flow rate and vehicle speed data, as well as the Banks emissions analyzer to measure fuel economy calculated from tail emissions. The dyno was calibrated to simulate a 7,500 lb vehicle with an engine output of 30 HP required to maintain a 50 mph steady state speed. The truck was warmed to operating temperature then held at a constant 50 mph for a fixed length of time to procure an accurate average fuel consumption. The test was repeated for all covers as per their respective manufacturer’s fill level specifications