You may have heard of an air filter in your car's cabin before, but what about the engine? The air filter in the engine controls the quality and quantity of air that reaches your vehicle's engine. All vehicles have an engine air filter, regardless of whether they have a diesel or a gasoline engine. The engine air filter keeps harmful contaminants like dust, pollen, and dirt out of your car's engine to avoid causing harm. Over time, the harmful contaminants can collect on the surface of the filter, which in turn can reduce the car's performance if the filter is not changed. If the air filter is clogged, it can also affect your car's fuel economy by reducing the amount of quality air that can reach the engine and the mechanical system.