Your owner's manual will list an address for the manufacturer. Choose a safe car. Look for the current safety inspection sticker required by your state. If it has been recalled, ask the dealer for proof that the defect has been repaired. Check prices at the library with the NADA Official Used Car Guide or used car pricing services.
Some states have laws giving extra protection to used car buyers.
Contact your state or local consumer protection office to find out what rights you might have. Check with your state motor vehicle department to research the car's title history. Get the written mileage disclosure statement required by federal law from any seller and make sure it matches the odometer reading on the car. Check the title to the car before you sign on the dotted line. Look carefully at the car in full daylight.