As a lot of the others are saying, go for the odd choice, something most of the age bracket doesnt buy.
Personally (although i was 19 not 17) I was torn between a Fiesta Zetec S and a ford capri. Same performance from both power and 0-60. But the capri was about 2k cheaper to insure.
So mid-small family car, or something unsual for a young person (Saab/skoda/land rover) would be your best bet.