I heartily concur with JEM.
the car is only useful IF the son purchases his own.
any teenager (a few years ago myself included) respects their own possessions when they buy them themselves.
if you give it to your son it will be less appreciated than if he buys it himself.
i am thoroughly disgusted when i see high school kids flying around town in new (or almost new) corvettes, hummers, or other signs of excess wealth (or stupidity) although my politics are showing, like 30,000 dollar sweet 16 parties, or prom parties, i think all this excess giving to kids, who don't even understand what it takes to earn the $$ is a huge disservice to the kids. (think of paris hilton!)
sorry to rant, but this does @#$% me off.