1. Go Easy on the Accelerator

This first tip is a no-brainer, but it's an important one: take it slow. Lead-foot drivers waste fuel accelerating quickly, and significantly hinder their fuel economy. Accelerate slowly, brake gently and you'll save a bundle on fuel costs.

On the highway, wind resistance is enemy number one. A simple rule of thumb: the faster you drive, the more fuel you waste. Automotive experts recommend keeping your speed at 55 mph for optimal fuel economy.

2. Dump the Junk in the Trunk

For every 100 additional pounds, a vehicle's fuel economy drops by 2%, so it's definitely worth your while to lighten the load. Remove golf clubs, roof racks, and other heavy items--but make sure you keep the spare tire.

3. Own a Diesel Engine? Fill up with Biodiesel

Biodiesel, the "clean" diesel fuel, emits less pollution than traditional diesel fuel. Derived from vegetable oils, animal fats and recycled restaurant grease, it makes fuel out of materials that would otherwise be poured down a drain.

Any diesel engine can burn biodiesel fuel without modification. Make certain the biodiesel you purchase is within the recommended grade for your engine.

4. Pump Up Your Tires

Keeping your tires properly inflated can increase your fuel mileage. The Consumer Federation of America (CFA) estimates that one-quarter of vehicles have improperly inflated tires. The average under-inflation, 7.5 pounds, results in a 3% loss in gas mileage.

5. Don't Drive!

Ditching your vehicle altogether is the best way to go 'green.' Riding public transportation, carpooling, bicycling, or walking can help you save you eliminate car payments, auto insurance premiums, and fuel costs. What's more, it can give you some good exercise too!