Tip #2. Check your air filter
Another gas saving tip is to ensure you have a clean air filter. An air filter is another key to good fuel economy and a way to improve gas mileage. A dirty air filter will restrict the flow of air into the car engine, which will harm performance and reduce fuel economy. Air filters are very easy to check and to change. It is one of the great ways to save gasoline and a gas saving tip; remove the filter and just hold it up to the sun. If you can't see light coming through the filter, you need to go get a new one. Also consider a permanent filter which is cleaned and not changed. They are much less restrictive than the throw away paper air filters. As an added benefit they are better for the environment.
You should definitely check your air filter every 20 thousand miles to have the cleanest filter in order to experience the greatest gas savings.
Potential Fuel Economy Benefit: up to 10 improvement in mileage%
Equivalent Gasoline Savings: up to $0.35/gallon