1. Avoid rooftop carriers.
Approximately one quarter of each gallon of gas is needed to overcome wind resistance, so avoid carrying things on your roof. If necessary, use an aerodynamic carrier to help minimize drag.

2. Remove junk from the trunk.
Added weight in your vehicle affects fuel economy, so take unnecessary items out of your trunk.

3. Go the speed limit. Use cruise control.
Speed limits are calculated for maximum safety – they'll also reward you with maximum gas mileage. You can get up to 20% more mileage traveling 55 than 70 mph. Using cruise control provides additional gas savings.

4. Drive evenly. Avoid hard stops.
Quick starts burn gas while hard stops also cost you. Take your foot off the accelerator and coast a bit before stopping for a traffic light or a stop sign.

5. Avoid idling and rush hour traffic.
You're burning fuel while idling – up to a gallon every hour. So, avoid rush hour traffic when possible.

6. Open windows at slow speeds. Use A/C on highways.
Around town, turn your air conditioning off and roll down the windows. On the highway, open windows create drag at speeds of 40 mph or more, so roll them up and use the air.

7. Don't accelerate up hill.
Build up speed before an incline, and then maintain it on the way up. Coast on the way down for additional fuel economy.

8. Fill up when it's cool and before holidays.
Cooler temperatures in the early morning or late evening create less vapor. Also, getting a fill-up three days before a holiday will help you save on the per-gallon price at the pump.

9. Don't top off gas and tighten the cap.
When buying gas, stop when the pump shuts off automatically. And remember, your tank needs both fuel and fumes, so tighten the gas cap after every fill-up.

10. Use the correct fuel grade, any brand.
Most vehicles don't benefit from higher-octane, higher-priced gasoline, so use the lowest grade recommended by your vehicle manufacturer. The federal government also has standards for gasoline to be sold. That means one brand of gas isn't better than another.

Find your GM dealer for expert Goodwrench services.

1. Change engine oil, using the recommended grade of motor oil.

2. Check and change your air filter.

3. Inspect and, if necessary, replace a clogged fuel filter.

4. Adjust tire pressure to manufacturer-recommended specs.

5. Inspect/clean intake system.

6. Inspect/replace emissions components and/or a faulty oxygen sensor.

7. Inspect brakes for proper adjustment.

8. Inspect power steering system and perform a steering alignment, if necessary.

9. Align front suspension

10. Clean or replace dirty or malfunctioning fuel injectors.

11. Inspect/replace spark plugs and spark plug wires.

12. Check exhaust for clogged catalytic converter.

13. Examine exhaust gas recirculation system.

14. Check automatic transmission/torque converter for proper fluid levels and shifting.

15. Inspect and clean coils and connections.

16. Examine/replace cracked or broken vacuum hoses.

17. Perform a high-mileage engine flush to dissolve and disperse deposits formed in the crankcase, cylinder walls, pistons, and rings.

18. Perform diagnostic check for stored problem codes on your vehicle's computer that indicate malfunctioning systems.