Thanks everyone for your suggestions and comments.
Regarding star trek - no problem, not my thing
(though growing up my parents and older siblings loved it).
I will definitely be setting rules and regulations, and the number of passengers will be strictly limited to the number of seatbelts the vehicle has. Of course he has to get a job to pay for our insurance increase when we add him to the policy, and he'll be paying for his own gas. Hopefully he'll realize pretty darn quick that at this age he's just gonna be working every hour he's not at school to earn money to buy gas to go to work and back, and not much else.
And yeah, he remembers being about 4 years old and in his carseat when we were rear-ended going about 30, and how my front upper tooth put a ridge in the steering wheel, and how his ice cream cone went all over the ceiling. Likewise about when I was broadsided in my driver's side door when I was driving home 4 months pregnant, and was put on bedrest until my daughter was born (3 weeks premature, and weighing under 5 pounds when we brought her home), and I beileve I'll be reminding him of those things