Depends on the young man and your wallet. We bought my son a 911 when he was 16 but immediately began restoring it and he finally drove it away to college the summer between his freshman and sophomore years when he was 19 almost 20. Spent a significant sum over those three years but only equivalent to about 5 weeks of drug abuse rehabilitation at a quality facility. It seems to be a lot more fun spending money on SSI's or P&C's versus lawyers and bail. Took a lot of wonderful time too.
I do not have the least worry about him abusing the car; not after slaving over it for three years.
Jim