Ah. The real price of this car is 90,000. My balance is 83,550. However, the price was listed as 13,000! I was surprised why I hadn't bought this car when I saw the price as 13,000. So when I tried to buy, it didn't give me the option to. I was looking at the price, my credits, again and again. It definately listed it as 13,000. I'm currently trying to recreate the error. And yes, it is the one remaining car I have left to purchase, so I didn't accidentally look at a different car or something!
EDIT:
I bought the car. Without thinking, I went straight into the car setup. This is the infamous buy->car setup bug. Crap.