I also lived at home, without a car, when I was your son's age, however, I never expected my parents to deviate from the a routine because I needed a ride somewhere WHEN I felt like waking up. I think it's commendable that you aren't angry at your son for staying out all night. (Something lots of people do at that age), but it was his choice, and his fault he was too tired. My suggestion would be tell him, "I am leaving in 15 minutes, with or without you."