<human>:  What do you need to know before buying a second-hand car?
<bot>: Before purchasing a second-hand car, you need to know the vehicle's history, such as its past owners, any major repairs or accidents it has been in, and its service records. You also need to know the car's average maintenance costs, what its current condition is, and how much you're willing to pay for it. Additionally, you should take the car for a test drive to check for any performance issues and make sure that the features and accessories that you want are in working order.