I'm 23 with a 700+ credit score who (except for $16k in student loans outstanding) had never taken out a loan before my Mustang purchase 2 months ago. Since we are in the same boat, credit wise, I can tell you that credit score means jack shit when you have no history of paying off loans (good or bad). The car was $22,500 and I had $6k to put down, and NO bank would give me a loan. Ford ended up financing it at a high rate of 7%. Car companies will extend statistically questionable loans to young people to gain your loyalty at a young age. So short of going to a dealership and begging them to finance you, you are pretty much stuck, even if you are very good for it (I am on pace to pay off my mustang exactly one year from the date I bought it).

Also, don't forget about taxes/fees/insurance. Taxes and fees brought my mustang purchase up to $25,500 (yes there are taxes for used cars). I have been driving since 16 and have a spotless driving record. My insurance is still $1500/yr for my mustang. Having a sports car at a young age is no joke in terms of the financial commitment. I haven't regretted it one bit, but it is a HUGE commitment. Good luck and let us know how it turns out. 4g63's are mindblowing when they run =P.

EDIT: My two best friends both applied for car loans around the same time as me. Both of them have significantly less student loans than me and both of them got denied. It's seriously hard to get a loan like that with no history, and when you do it will be an extremely high rate like mine. If you have the means to churn through the payments fast like I am, its a much better deal.

1991 Mitsubishi Eclipse GSX - SOLD
2006 Mustang GT Convertible