Kim the in-house mechanic for Driverside shows you how to quickly and easily replace your cars air filter. The reason you would need to change your air filter is that over time the flow is reduced which consequently reduces your car's gas mileage. To change your air filter you first need to locate it on your car. The air filter is under the hood and usually in a box that either has clips of fillip's head screws holding the cover on. Remove these to gain access to your filter. From there you can look to see if you filter is dirty and replace it if necessary. When you've finished simply reattach the cover with the screws or clips and you're good to go.