High-performance air filters can make a difference in your car's performance, fuel economy, and acceleration. Replacing a clogged air filter can increase fuel efficiency and improve acceleration, depending on the make and model of your car. How does an air filter make such a difference? A dirty or damaged air filter limits the amount of air that flows into your car's engine, causing it to work harder and therefore consume more fuel. It is recommended that you replace your air filters at least every 12,000 to 15,000 miles (19,000 to 24,000 km).
This interval should be reduced if you often drive in dusty conditions. You'll get about 1BHP more from a good quality filter, but unless you're the princess who slept in the pea, you won't notice. What better quality filters DO have is that they take longer to clog. A high flow air filter can increase your horsepower by about 3 to 5 HP and also increase your torque.
At the same time, this can lead to higher fuel efficiency. How? In some of the more expensive units, the filter comes with a cold air intake unit. It is installed to extract air from the outside of the car instead of the hot air used inside the engine compartment. Cold air is denser and therefore will burn better, thus improving your engine performance.
Stainless steel mesh is another example of an air filter medium used to produce an aftermarket exhaust. Clogged air filters can reduce airflow to the engine, literally drowning it out and, as a result, affecting the car's emission control systems, causing incorrect air-fuel mixing and spark plug ignition problems, which can lead to serious driving problems. Cotton gauze air filters have several advantages; first of all, these filters are washable and therefore do not need to be discarded; they last the entire life of your vehicle. For every gallon of fuel burned, the engine consumes up to 10,000 gallons of air, so it's easy to understand how important a clean air filter is to the proper operation of a car.
Often chosen for off-road rallies and other motorsport activities, foam air filters have a higher filtration capacity than their aftermarket counterparts and can therefore flow stronger for longer.