For some reason I can't get this thread out of my mind so I called my financial advisor about this to see if in reality this could happen (17 year old buying a 60-90,000 dollar car). She told me that without a HUGE (roughly half of the total 30K) down payment its basically not possible. No bank is going to back that kind of money. Her only client right now that can afford this type of vehicle (price range) makes roughly 135,000 a year and she approved him to buy a BMW M6 (97k).
I don't think an insurance company would cover an 18 year old in a high performance sports car either.
Keep dreaming though, it gives you something to set your sights on. I know that sounds harsh, I really don't mean it that way. People on here may give you crap and call you stupid, but if you REALLY think you can do it than work hard and set a goal.