Replacing a clogged air filter can increase fuel efficiency and improve acceleration, depending on the make and model of your car. But, don't expect a bunch of extra ponies to suddenly appear when you hit the accelerator. It's always best to follow the vehicle manufacturer's recommendations. The numbers are small and you probably don't feel the extra power.
However, there are at least 5 benefits of changing your air filter regularly: better gasoline performance, reduced emissions, improved acceleration, longer engine life, and overall improved driving. If you are coughing and sputtering, or if you vibrate excessively when you turn the engine, you are most likely ordering a new air filter. Other names by which automotive air conditioning filters are known are micron air filters, cabin air purifiers, cabin air filtration systems, and cabin air dust filters. The car cabin air filter in your vehicle's ventilation system is used to filter dust, allergens, mold, particles, and sometimes even odors from the air entering the passenger compartment of the car.
Over time, as dust and dirt build up, the air filter will darken and dirt will be noticeable. Air filter replacement can be part of a general tuning service that will help you get better mileage and performance out of your vehicle. The EPA has not tested oil-bathed filters or other free-flow air filters, but it has conducted tests that compare conventional clogged air filters with new ones. Changing just the air filter can disrupt the way a car's engine works with the gearbox and transmission.
Regardless of the exact numbers, it's obvious that a clean air filter improves airflow to the engine and increases engine performance and fuel consumption. If you've ever been to an auto parts store, you've probably seen air cleaner boxes that claim extra power and more torque than the factory filter. Well, Jason Fenske from Engineering Explained tested these claims, and it turns out that yes, high-performance air filters actually produce more power. He tested each filter with a dynamometer and then measured the acceleration with a VBox to see if any data learned from the test bench translated into the real world.
The aftermarket filter generated more power, but Fenske wondered if it actually filters less overall as well.