Got a gas-guzzler? Here's how to cut down on fuel costs

If you're not ready to buy a more fuel-efficient car, you can still save money in whatever vehicle you drive.

The biggest fuel savings comes not from hybrid technology but from the old standards: car pooling and public transportation. If you and just one friend or neighbor trade off commuting to and from work, you cut your fuel usage by about 50 percent. No other step will save you as much money. Also, if you have two vehicles in the family motor pool, leave the thirstier one in the garage as often as possible.

Public transportation saves fuel, and possibly money. It also decreases congestion, which saves everyone fuel. Help yourself and everyone else .

Weight is fuel economy's natural enemy, so removing unnecessary items from your car can translate to real fuel savings.

You can save fuel immediately in whatever you drive by going easy on the accelerator. Jack rabbit starts and full-throttle acceleration boost fuel consumption dramatically. It's all a matter of degree: Light acceleration saves more than moderate acceleration.

Top speed also plays a part. Most vehicles are most efficient when cruising in their top gear at a relatively low speed. For example, a car with a five-speed transmission would be most efficient in fifth gear at 40 to 55 miles per hour. Wind resistance increases exponentially with speed, so as your pace increases from this point, fuel economy drops dramatically. Onboard trip computers that show instantaneous and average fuel economy are remarkably accurate. Keep an eye on this and you'll learn how to drive in a miserly fashion.

Keeping your tires inflated properly and your engine running right is critical to efficient motoring. Underinflated tires can lower your fuel economy by full miles per gallon. (Get the proper inflation pressure from the sticker on your car's doorjamb or the owner's manual, and not the tire's sidewall.) Even if your car seems to be running well, that perplexing "Check Engine" light could represent a dead oxygen sensor or some other emissions control problem that causes the vehicle to waste several miles per gallon.

Traveling with open windows or the air conditioning on is an age-old conundrum. Unlike a car's heater, which uses free engine heat to warm the cabin, the air conditioner robs engine power and lowers fuel economy. So which approach is better? It's not as simple as one or the other.

If your car has been sitting in the sun and is hotter than the outside air, drive for a few minutes with the windows open to cool it off. Then, if you're hitting the highway, close 'em up and turn on the air conditioning. Aerodynamics are more important at high speeds, so if you're not exceeding 35 or 40 miles per hour, open windows won't make as much difference. It also depends on the vehicle. The detriment from driving with the windows down is greater, say, in a Chevy Corvette, which has excellent aerodynamics, than in a Hummer, which has . . . none. The same applies to convertibles; you'll burn less with the top up.

Speaking of aerodynamics, roof top carriers and bike and ski racks don't do you any favors -- even when they're empty. If you keep all your cargo inside the car, you'll slip through the wind better. Also, strip off any aftermarket add-ons such as bug deflectors and window and sunroof wind deflectors. By design, these items work by wrecking your aerodynamics. Sure, bug entrails on your windshield are gross, but they aren't known to cost you any fuel.

And as for the fuel itself, lower octane costs less, and most modern cars that call for premium fuel can run on regular gasoline without knocking or any long-term penalty. Technically, this makes the car less efficient, but not to a degree that negates the cost savings from the cheaper fuel grade.