2 per car. The engine air filter has one job, to keep dirt, dust, and other damaging particulates out of your engine. When your air filter is old or worn out, it clogs the main passageway to your engine, effectively suffocating power and fuel efficiency out of your daily commute.

Often times made of fibrous paper or fiberglass type substrates, it’s important to buy a high quality air filter to avoid an over-restrictive filter matrix. Some filters, such as K&N, feature washable elements to make them reusable, and oftentimes these are made of a cotton substrate that offers much better flow. If you are feeling power loss and you haven’t replaced your air filter in a while, it might be a good time to replace it.