Gas prices are high, causing many drivers to look for ways to improve fuel efficiency. Although there are practical steps you can take to increase gas mileage, the Federal Trade Commission (FTC) suggests that you proceed with caution when you consider buying automotive devices or oil and gas additives based on gas-saving claims. The FTC says that even for the few products that have been found to work, the savings to consumers have been small. According to the FTC, it's wise for drivers to be skeptical of the following kinds of advertising claims: "This gas-saving product improves fuel economy by 20 percent." Claims usually tout savings ranging from 12 to 25 percent. However, the U.S. Environmental Protection Agency (EPA) has evaluated or tested more than 100 alleged gas-saving devices and has not found any product that significantly improves gas mileage. In fact, some such products may damage a car's engine or cause substantial increases in exhaust emissions. The products on the market that claim to save gas fall into clearly defined categories. Although the EPA has not tested or evaluated every product, it has tried to examine at least one product in each category. Check www.epa.gov/otaq/consumer/devicefs.pdf for category descriptions and product names of devices tested by the EPA. "After installing your product on my car, I got an extra 4 miles [6.4 kilometers] per gallon [3.8 liters]." Many ads feature glowing testimonials by satisfied customers. Yet, few consumers have the ability or the equipment to test for precise changes in gas mileage after installing a device or using a product that claims to save gas. Among the many variables that affect fuel consumption are traffic, road and weather conditions, and the car's condition. Take the example of the consumer who sent a letter to a company praising its purported gas-saving product. At the time the product was installed, the consumer had received a complete engine tune-up -- a fact not mentioned in the letter. The entire increase in gas mileage attributed to the product may well have been the result of the tune-up alone. But other consumers couldn't have known that from the ad. "This gas-saving device is approved by the federal government." No government agency endorses gas-saving products for cars. The most that can be claimed in advertising is that the EPA has reached certain conclusions about possible gas savings by testing the product or by evaluating the manufacturer's own test data. If the seller claims that its product has been evaluated by the EPA, ask for a copy of the EPA report, or check www.epa.gov for information. In some instances, false claims of EPA testing or approval have been made. Product Complaints and Refunds If you're dissatisfied with a gas-saving product, contact the manufacturer and ask for a refund. Most companies offer money-back guarantees. Contact the company even if the guarantee period has expired. If you're dissatisfied with the company's response, contact your local or state consumer protection agency, the Better Business Bureau or the FTC. The FTC works for the consumer to prevent fraudulent, deceptive and unfair business practices in the marketplace and to provide information to help consumers spot, stop and avoid them. To file a complaint, or to get free information on any of 150 consumer topics, call toll-free, 1-877-FTC-HELP (1-877-382-4357), or use the complaint form at www.ftc.gov. The FTC enters Internet, identity theft, telemarketing and other fraud-related complaints into Consumer Sentinel, a secure, online database available to hundreds of civil and criminal law enforcement agencies in the U.S. and abroad.