Here's some tips I found:
1.
Keep your engine tuned up. Incorrect fuel ratio, bad spark plugs and incorrect spark timing can have a big effect on gas mileage.
2.
Don't use your air conditioner (A/C) unless you really need it. The A/C compressor puts an extra strain on the engine.
3.
Make sure your tires are properly inflated. Under inflated tires cause more resistance to travel.
4.
Avoid stop and go traffic by taking alternative routes or less congested travel times.
5.
Ask other people with the same type of car what kind of gas mileage they get, it may alert you to a problem with your car.
6.
Use a good engine oil, preferably a synthetic or standard oil treated with a friction reducing oil additive. These have been known to improve fuel economy by as much as 12%.
7.
Reduce the weight in your vehicle as much as possible. (Good excuse to get the mother-in-law out of the car....)
8.
Use your cruise control whenever possible.
9.
Keeping your highway speed at 55 mph can improve you gas mileage by as much as 25%, compared to 75 mph. (Yeah, I know--this one's tough for us too)
10.
Avoid trying to increase speed while climbing a hill, your engine is already working hard trying to overcome gravity.
11.
Keep your windows closed when possible. Open windows actually reduce gas mileage compared to using the A/C.
12.
Remove accessories, such as luggage rack, etc. that lower the aerodynamics of your vehicle.
