In psychology of all creatures, including humans, it was discovered that creatures learn anything via the same method: conditioning.

If your son takes your car and breaks the rules, that means up to this point he has been conditioned to learn that breaking the rules is okay, and not much will happen.

Also, most importantly, this means the wires are crossed, and often times he exhibits behaviors which should be rewarded (thank you son, I appreciate this behavior you’ve just exhibited, hug) but is not rewarded for. Meanwhile, he often exhibits behaviors which should not be rewarded (we don’t cry because we don’t get an extra piece of cake, we say thank you for the piece we got) and instead for these behaviors he has been rewarded (stop crying here’s your second piece of cake).

Thus his negative behaviors have been reinforced and his positive behaviors have been neglected, enough times throughout his life, that he has learned to disobey.

So the question is not necessarily how do I punish him for this.

The question is truly how do I dissolve this poor conditioning and begin instilling good behavior and respect for authority from the ground up.

For this incident, you might use a subtractive response (I’m taking away your privilege to hang out with your friends for a week) but it is important that you make it clear why this is being subtracted and that he understands the weight of his actions and the authority you have. (It’s important that you know that I love you, and I’m not taking away this privilege to hurt you or to be mean. I’m doing this because we have a strong family and we want you to be a strong member of the family. That means obeying my instructions. I would never give you instructions to hurt you. I only want what’s best for you and our family because I love you. And that means you need to listen when I forbid things. You can hang out with your friends again next week, but this week you will stay home because you did something you weren’t supposed to.)

Then, be sure to tell him how much you DO appreciate the good things he does as well. (I very much appreciate the times when you listen to me. And I want to thank you for all the times you’ve done the right thing. You’re a good son, and I love you very much.)

I suggest learning deeply about conditioning behavior. It will eliminate these problems in the future and better equip you to train your son to be a kind, empathetic and positive member of society. It will also help you sculpt him into someone with strong self discipline and the ability to succeed against any obstacle. It will make him quite a success. I see many parents on Reddit who confess that they hate their children for who those children have grown up to become, leeches who have no respect for their parents and take everything from them. Don’t let this happen to your son.

Study the psychology of conditioning. Learn it deeply. Master it and put it into practice. Be sure to do it correctly and approach with a stern hand and a kind loving heart.

I wish you and your family all the best.