1. Slow Down
Speeds over 40 miles per hour (mph) creates incredible wind resistance that your car must overcome. This increased resistance causes your car to burn more fuel. Traveling at 55 mph give you up to 21% better mileage when compared speeds of 65 mph and 70 mph.
2. Shift Gears
Running your automobile at high speeds in low gear can use 45% more fuel than if you were in the right gear.
3. Keep Windows Closed on the Highway
The increased drag caused by open windows can reduce gas mileage up to 10%.
4. Drive Proactively
Slowing down and speeding up wastes fuel. Also, accelerate before approaching a hill rather than when you are climbing it. You engine is forced to work harder on an incline, thus reducing gas mileage.
5. Avoid Rough Roads
Dirt and gravel roads can reduce gas mileage up to 30%.
6. Keep Your Car in Good Working Order
Make sure tune ups and oil changes are up to date. Also, make sure you tires are properly inflated. A well-kept car requires less stress on the engine and increases gas mileage.
7. Remove Excess Weight
All of the junk that some people accumulate in their cars can start to add up. Trunks filled completely and other excess weight causes the engine to work harder. Whenever the engine needs to work more, fuel efficiency decreases.
8. Don't Idle for Long Periods of Time
Idling for one minute equals the amount of gas used to start the car's engine. If you are forced to sit at an idle, put the car in neutral. Using neutral reduces strain on the transmission and allows it to cool.
9. Don't Warm Up Your Car
Older cars required time to let the engine start working. Newer cars are designed to start cold.
10. Accelerate Slowly
Taking off to a fast start burns fuel unnecessarily. This is equal to revving the engine.
Thanks to: About.com