1. Don't top off. It spills gas, and the evaporative vapors contribute to ozone.

2. Gas up at night. More gas evaporates during hotter weather.

3. Combine trips. Several short trips taken from a cold start can use twice the fuel as a single trip covering the same distance when the engine is warm.

4. Double-nickel drive. 55 mph gets the best highway mileage.

5. Tune up. Dirty parts make engines less fuel efficient.

6. Avoid rabbit starts. Slow acceleration uses less gas.

7. Drive a 5-speed. Manual transmissions use 5 percent less fuel.

8. Stay in shape. Fuel economy decreases by 1 percent to 2 percent for every extra 100 pounds of auto weight.

9. Garage your car. The bus is going there anyway.

10. Buy a hybrid. Electric/gas cars get great mileage with minimal pollution, and you don't have to plug them in. Plus, they're cool.

Sources: City of Boulder, Colo.; U.S. Department of Energy; and the California Energy Commission Consumer Energy Center.