If the kid is being bombarded with different offers, it would be much more difficult.
If the kids parents are with him and helping him make the choice, you'll probably need to sell more substance.
I'd guess it would be much easier for a used Porsche dealership to sell a car to a 17 year old than those crappy little dealerships with like 15 cars and a sign in front that says "No Credit Checks!".
I guess the answer is. . . it depends.