That air filter replacement interval drops even more if the vehicle is used in dusty areas or extreme-use situations. Your auto air filter plugs up and gradually loses its efficiency over time, flowing less and less air until your car or truck is literally choked. The result is poor fuel economy and sluggish performance even though your air filter may not look that dirty. The answer is simple and inexpensive: A replacement air filter. We produce replacement air filters for most makes of cars, trucks, and SUVs, so don't neglect this essential but easy-to-forget part.