I remember my first car I got when i was 17 - it cost $850. it lasted me four years. It was replaced with a car that was worth $2,500.

I know a couple of people who have gone out and bought cars when they were in their late teens and early 20s. one had his car stolen (with no insurance) and ended up with $18,000 debt for nothing, the other had an argument with his mum about taking out a loan for $15,000 for his car, and now 5 years down the track, he realized she was right (he should have bought some land and a house).

Cars just aren't worth the money - they are merely liabilities. Your SDD is going to have to figure that out the hard way. just don't be tempted to bail her out when the poop hits the fan, otherwise she will never learn.