Gasoline prices have risen 33 percent this year, and with the average cost of gas now at more than $4 a gallon, Americans are struggling to stay on the road without breaking their bank accounts. Some businesses, though, see an opportunity to make money by selling supposed fuel boosting additives or offering engine modifications to help drivers conserve fuel. Better Business Bureau advises consumers to stay away from gas-saving products, parts and modifications that sound too-good-to-be-true and suggests more reliable ways to conserve fuel.

Over the past decade, the Environmental Protection Agency has tested more than 100 gas-saving devices and hasn't identified any that significantly improve gas mileage. Energy and Environmental Analysis Inc., a technical consulting firm in Washington, D.C., estimates that 99 percent of the aftermarket products do not really change fuel economy.

The EPA says that the majority of such products are harmless to vehicles but that testing has found that some products can cause substantial increases in exhaust emissions, thereby increasing the chances of actual engine damage.

With the cost of oil nearing $150 a barrel -- and gas pushing $5 a gallon in some parts of the country -- additives and gadgets to help conserve fuel are tempting for cash-strapped consumers. Unfortunately, these devices and additives will end up only draining the driver's wallet without adding a boost to their tank.

BBB says consumers are being inundated with ads that play off frustration and concern over high gas prices. One Web site asks: "Do You Want to Know RIGHT NOW How You Can Drive Around Using WATER as FUEL and Laugh At Rising Gas Costs, While Reducing Emissions and Preventing Global Warming?"

Another site boasts to "have discovered some little-known products that can actually help you increase your fuel mileage 10 percent, 20 percent, 40 percent and possibly more!"

Despite advertising claims, the bureau advises drivers that there is no simple, single way to improve fuel economy.

BBB recommends being particularly skeptical if advertisements claim federal endorsement. Though the EPA does evaluate the legitimacy of claims made by companies that produce gas savers, no federal agency actually endorses gas-saving devices or additives.

Marketing materials or Web sites for gas savers often contain testimony on the increased fuel efficiency that consumers experienced with the device or additive, but these are often works of fiction devised by the company.

Before buying a gas-saving device or additive, check out the company's reliability report at www.bbb.org.

The vast majority of gas-conserving products do not squeeze mileage out of vehicles, but there are a few basic steps that drivers can take to increase fuel efficiency and get the most out of their gas tank:

STAY WITHIN THE SPEED LIMIT. Stay within the posted speed limits because gas mileage decreases rapidly at speeds above 60 miles per hour.

AVOID "JACKRABBIT" STARTS AND STOPS. Drivers can improve gas mileage up to 5 percent around town if they avoid jerky starts and stops. This means accelerating slowly from a dead stop and avoiding pushing the gas pedal down more than one-quarter of the way; this allows the engine to function at peak efficiency.

USE OVERDRIVE GEARS AND CRUISE CONTROLS. Cruise control and overdrive gears improve fuel economy on the highway.

USE THE AIR CONDITIONER. Using the air conditioner at lower speeds will decrease fuel efficiency, but, at higher speeds, opening the windows might create significantly more drag than the air conditioner, reducing gas mileage by 10 percent.

REMOVE EXCESS WEIGHT FROM THE TRUNK. An extra 100 pounds can reduce a typical car's fuel economy by up to 2 percent.

KEEP THE CAR PROPERLY MAINTAINED. The engine should be tuned, tires inflated and aligned, the oil changed on schedule, and the air filters checked and replaced regularly. Replacing clogged filters can increase gas mileage up to 10 percent in some cars.

Kelvin Collins is the president and CEO of the Better Business Bureau of Central Georgia & the CSRA Inc. This tips column is provided through the local BBB and the Council of Better Business Bureaus. Questions or complaints about a specific company or charity should be referred to (800) 763-4222, www.bbb.org or info@centralgeorgia.bbb.org or info@csra.bbb.org.