When you buy a used car, don’t just kick the tires. In 2013, 3.5 million used cars with unfixed safety-related recalls were listed for sale on Craigslist and other websites, says Carfax.com. Recalls, registered with the National Highway Traffic Safety Administration, can range from a risk of engine fire to a defective airbag. To check whether a car has been recalled — and if so, fixed — you can look up its vehicle identification number for free on Carfax’s site. If a repair hasn’t been made (no cost at an authorized dealer), try for a price break in return for taking the car in yourself. Don’t have the VIN? The NHTSA’s safercar.gov lists recalls by make and model.