In other cars that I have owned, k&n has helped the gas mileage. However, honda seems to have already tweaked as much as they could to obtain the most mpg's. I have K&N installed in lx sedan and think for the $40 I spent, it is one of the best upgrades I have done. IMO...seems to idle and accelerate a little smoother...I took the K&N out last weekend to clean it, and put the stock filter back in while doing so. Had to make a quick run to the store and could tell a difference with the stock filter back...Definitely worth it IMO...Spent $40 shipped at autoanything.com...took 3 days to arrive...Hope this helps...