In a perfect world, every car seller is perfectly honest and knows every fault with the car he or she is selling. But we don’t live in a perfect world, so here’s how to act and what to look for so you don’t get screwed buying a used car.

Donut Media put this little explainer video together with a number of excellent step-by-step points. The first would be that only dorkwads buy E36 M3s BMWs and real macho makers get E34 M5s. Haha, I kid. Seriously, here are their points.

The idea is to learn what the car can tell you so that you don’t have to trust the inherently untrustworthy seller. If you do all these steps, you either buy a good car or walk away from a crapcan—but either way, you won’t get screwed.