[sdorn]

If your parents gave you the money, then there is no issue. Each one of your parents can give you a gift of up to $11k per year (that was the number as of 2005, it might be higher now) for a total of $22k per year with no tax consequences. You can give it to the car dealer in cash or by check, and even if the IRS asks where it came from (which they probably won't) you can just say your parents gave it to you. No big deal.

I would bet that with a 50% downpayment and any job where you can show you make enough to make the payments, you are going to be just fine.