Tip 21: Use Less Expensive Gas

Unless your car is knocking and pinging, don't use a higher octane gas than your owner's manual recommends. For most cars, premium gasoline offers no benefit. Unless your car has a high-performance engine and your manufacturer recommends a high-octane gas, use the less expensive gas. Premium gas costs 10% to 15% higher than regular. 

Potential Money Savings: $200-400/yr.

Tip 8: Cleaning the Air Filter

Check your car's air filter monthly. A dirty filter shortens the engine's life and reduces gasoline mileage up to 10%. You can clean the filter by removing it and blowing it with an air hose, or you can replace it. 

Potential Money Savings:  $130/yr or more.