First of all, have a heart to heart talk with him to see why he tried it in the first place...peer pressure?, experimenting? See if your son will open up to you. If he will not, which most teenagers find it difficult to do at this age, then tell him exactly how you feels about his actions. If this has been a first time occurrence, an depth talk will do for now. If this behavior continues, then tell your son what the consequences that he will face..not driving the car, no computer, cell phone, t.v., or video game time, limit free time with friends etc. You want to provide a consequence that will have an impact on your son.
If this has helped, please ACCEPT. Have a great day!!!!