What is the better car for me?

[Jusin Bieber is GAY!]

I'm 17 and i want to buy a car to last me until i'm done school probably 5-6 years. I've got currently $11,000 for a car and i make roughly $7,500 a year that can be put towards the car. I turn 18 soon and could start financing with a car with a cosignature. I want either a Mustang, Challenger or Camaro. Pretty much a car where everyday is a Saturday. If I go new I can probably only afford the base model for each car. Money will be tight and all my money will be going to payments. They'll make it work at the dealership, but after gas and insurance, what will be the point. I'll be just a guy with a nice car broke as h*ll with no gf.
OR
I could just get a >05 used Mustang GT probably borrow a little money from my parents buy it out right and won't have to worry about interest and no burden for the next 5 plus years. Just have to pay off my parents like 5K.

Whats more realistic. I love the Challenger but whats the point of puttinng all your money into something and only having one small thing for show.