I drive the same route every week, a total of 75 miles round trip at highway speeds (60mph), drive intown approx 30 miles a month giving me a total of around 325-330 miles a month. I checked my mileage with the factory type air filter/intake system and I averaged 15.15 mpg with 3.73 gears and the 5.4 L 3-valve motor. Mileage with the stock intake and a K&N flat panel filter increased to 15.73 mpg. I installed the Airaid Jr. intake with the K&N filter and mileage increased to 16.06. I then put the stock type (Fram) flat panel air filter back in the Airaid Jr. and averaged 16.63. The motor pulls harder with the K&N filter with the Airaid Jr. but also loses almost .5 mpg. Truck is a F-150 2006 Supercrew with a stock exhaust and no other mods and 50psi in the tires.