Wow. Last summer i average upper 16's with mostly backroad driving. This winter it went down to low 16's with 50% highway (75mph), 25% backroad, and 25% city. I've never got above 17.1 mpg no matter how easy i drive. Anyways i got a K&N intake... first tank after i installed it was 16.1, 2nd was 16.5 and i drove normal, and 3rd was 17.9 driving 80% backroads and 20% city with a light foot (shifting around 2200 rpm, letting off gas a little early and coasting a little more before braking)! Guess the ecu adjusted

Oh and these are 3.4% low bc my tires are larger than stock so i actually got 18.5 mpg!