Buying a car at an auction is a great way to save money. In fact, many people run their own businesses by flipping cars that they’ve purchased at an auction. But auctions are very different from purchasing a vehicle at a dealership; there are a lot of things that can go wrong if you don’t do things the right away. Here are a few things that you need to know.

You Need to Pay For (And Take) the Car Right Away

When you purchase a car at an auction, you need to be able to pay immediately and you need to be able to take the car off the lot. If the car isn’t currently in operable condition, you’ll need to tow it or use an auto shipping company, like Great Guys or UShip. Otherwise, you need a licensed driver with you. Payments at auction houses generally need to be in the form of cash or money orders, so make sure you have adequate funds beforehand.

You Need to Be Able to Identify Large Problems

You don’t get a lot of time to inspect the cars at an auction. Generally, you’re able to look at the vehicles for a short amount of time before the auction starts. If you aren’t a mechanic yourself, it’s a good idea to bring one with you. They’ll be able to help you avoid the most significant issues.

Unfortunately, the most expensive issues to fix in a car tend to be the least visible. A blown engine, bad transmission, busted head casket, or malfunctioning air conditioning compressor could all cost thousands of dollars to fix. A good mechanic will be able to identify these things within a few minutes of operating the vehicle; a regular driver might not.

You Need to Know the Real Value of a Car

What goes into the value of an auctioned car? The same factors as any used car: make, model, year, odometer reading, and general condition. The challenge is that you have very little time to determine this during the auction itself. But the good news is that you often don’t have to.

Many car auction sites will list the vehicles that they have for auction far in advance. You can then look up the Kelley Blue Book prices or True Car value of these vehicles at your leisure. Keep thorough notes regarding the cars and you can avoid getting locked into a bidding war that greatly exceeds the marketable value of the vehicle.

You Need to Handle Legal Matters

Most people aren’t purchasing a car at an auction to use — they’re purchasing it to resell. If you’re reselling cars, you should be aware that you can only resell a certain number of cars per year before you need to get a dealership license. And even if you’re purchasing the car to use, you should still make sure that there are no holds on your license and that you can easily register the vehicle under your name.

An auction for a vehicle is just as high stakes as an auction for anything else. But if you know a lot about cars — and are willing to take some chances — you can often get a tremendous deal on cars, far below market price.