The problem for young people is that they are cursed with a serious belief that they are invulnerable, and bad things happen to others, not to them.
This gradually wears away thanks to the twin experiences of living life, and gaining maturity, and seeing and realising that the world is a dangerous place if you are silly and irresponsible in it.
As a parent, all you can do is lay it our for him - If you do this, this will happen, if you do that, that will happen, and hope he takes some of it in.
When giving him this information, it is essential that you avoid even hinting that you are talking from the voice of experience (even though you are!) - which leads to instant shutdown.
Tell him you love him, and tell him, that you try never to say or do anything you would not want him to see or hear, and maybe he could try the same thing.
Ask him to think a bit, look ahead, and to remember that life is not a soap opera, and fast cars don't bounce like they do in action films, and consequences do happen.
Good luck!