Does adding an aftermarket air intake system improve gas mileage? If so, is it significant?

i think it depends...i have a K&N air filter on my civic...i thought it would improve gas mileage...but its still the same, then after a few months my car became less fuel-economic...dont know why...thats when i found out the bigger the intake, the more gas consumption...tune up ur car and change oil atleast once a month, or in my case every 5000 kilometers...also clean ur air filter once a month...

go with aither AEM or K&N they are the best.

if youre going to buy a CAI there are some that truley do improve performance. before making a choice on which brand go to a rsx forum. there will be reviews on there somewhere of which ones actually work and which ones dont. an independent study was done for my car and it was proven all CAI actually caused a LOSS in hp and fuel efficiency except 1. that is a AFE stage 2 CAI which is about $350. the K&N actually was one of the worst out of the group. DO NOT go by what the company tells you. always be sure to find independent studies on the matter. hope this helps

I have a Comptech Icebox on my '02 and saw negligble MPG impact but a slight improvement in HP (4-5 est.). Theoretically they should help, as colder air is denser and heat is the enemy of efficiency, but the impact is going to be very minor at best.