Your car contains many filters that are designed to prevent contaminants from entering your engine, corroding it and disrupting the normal operation of the engine. Otherwise, you will suffer from performance drops and the engine might even become damaged. There are also filters that are designed to improve the air quality of your car, such as the cabin filter. If the filter becomes clogged or damaged, you will need to have it replaced to maintain the air flow of your AC and to maintain adequate air quality.
Many municipalities have different requirements for the vehicles that are registered within them. Since the environment is an important consideration in this day and age, a number of states require you to receive a smog inspection. This test, also known as a smog check or an emissions test, measures the cleanliness of the components that your vehicle is expelling. A lower emission vehicle is better for the environment and less harmful, while older or poorly maintained vehicles have more noxious emissions.