Does Changing a Car’s Air Filter Really Save on Gas Mileage?

Almost anyone who owns a car is looking for gas saving tips, particularly ones that promise that if you do this thing you can save up to 14% on their car’s gas bill. Changing an air filter is simple enough that just about anyone can do this in five minutes, even if not super comfortable around the innards of a car. Promising that it can save you big money on the cost of car mileage gets it listed on almost every list of ways to save money on your car.

An air filter is a critical part of a car’s engine. An air filter prevents things from getting sucked into an engine. It needs good, clean air to power combustion to move the pistons.

It makes sense to car owners that as an air filter becomes clogged, it slows air from getting to the engine. It seems intuitive that this would then impact car mileage.

shutterstock_102154228The truth is that it once used to. Older cars that used carburetors could see a big impact. Modern cars use computer controlled systems and fuel injectors to mix the air and gas. That means a modern car can adjust to the dirty air filter.

What will be impacted is acceleration. Because the car won’t be able to suck as much air as it needs, when the driver hammers the accelerator the car will, efficiently, deliver less horsepower because it will be mixing less fuel in with the air but keeping the ratio just right for efficiency. To keep the pep going in a car, manufacturers suggest changing filters every 30,000 miles to 45,000 miles.

One way changing air filters can actually save a car owner money is by not waiting too long to change them. In theory, a very dirty, clogged, or even damaged air filter could stop doing what it was designed to do: prevent particulates from getting sucked into the engine. If that were to happen abrasive bits could get into the engine and cause damage.

It’s unlikely it would completely kill the engine but it could shorten the life of the engine. It could also cause the engine to stop running until a new one was installed.

So even though it won’t save big money, it’s a good idea to change a car’s air filter before it gets to that point.

Fortunately, the one part of the ‘tip’ is true: it’s easy to change a car’s air filter: