As gasoline prices remain high, consumers are wondering what they can do to improve their gas mileage. Although there are practical steps you can take to increase gas mileage, the Better Business Bureau warns consumers to be wary of gas-saving claims that empty your wallet, instead of saving you fuel. Many Web sites make unbelievable claims for various aftermarket automotive devices (fuel-line magnets, air bleed devices and retrofit gadgets) and oil and gasoline additives that supposedly increase gas mileage for automobiles. The Federal Trade Commission found many of these claims to be either false or overly exaggerated.