How can I check for rust when buying a used car?

When buying a used car, you should inspect the car carefully for rust. Look under the car and along the wheel arches, door edges, and under the door frames. Use a flashlight to illuminate dark areas. You can also use a magnet to check if a lot of filler has used instead of metal, which may indicate previous rust repairs. It is also a good idea to have a mechanic inspect the car for hidden rust damage.