Improving Gas Mileage 2

Keep Your Car In Shape
 -Fixing a car that is noticeably out of tune or has failed an emissions test can improve its gas mileage by an average of 4 percent. 
-Fixing a serious maintenance problem, such as a faulty oxygen sensor, can improve your mileage by up to 40%

Keep Tires Properly Inflated
While also being safer to drive, maintaining proper inflation levels in tires effect your gas mileage by 2-5%! It will also help make your tires last longer saving money there as well.

Use the Recommended Grade of Motor Oil
Ever change or top off your own oil? Well make sure you check what kind its supposed to take. 10W-30, 5W-30 ,5W-20 are obviously labeeled differently so choose the correct one for your vehicle. Another tip is to look out for Energy Conserving oils that include friction reducing aditives. Were looking at a 1-3% mpg increase here folks.

Replacing a Clogged Air Filter on Modern Cars Improves Performance but Not MPG
I've always thought having a dirty and old air filter cold effect my mpg. But I guess I was wrong and the myth has been dethroned.  While replacing filters does not improve fuel economy  it can improve acceleration time by around 6 to 11 percent. Its also important to realize that this is for "newer" cards made in the 1980's and forward. Tests do show that older cars suffer a 2-16% reduced mpg reduction with old filters. Yikes!