1. Avoid accelerating or decelerating quickly.
2. Obey speed limits.
3. Find the lowest gas prices around.
4. Don't leave the car running, even just for a few minutes.
5. Lighten your car's load.
6. Buy gas early in the morning or late in the evening.
7. Maintain your car with regular service checkups and keep your tires inflated to the correct pressure levels.
8. Combine trips whenever possible.
9. Drive in the correct gear.
--as adapted from workitmom.com