If the truck driver was negligent in some way that caused the wreck (of course they were, or there would not have been a wreck), then you may have a right to damage claims.
Most of the time though, you don't. That's the way the system works. It's not very fair, but it's better than some countries that penalize everyone, or no one. At least they paid for the wrecked car (mostly).
The way to find this out for sure is to get a lawyer. A down payment on a car isn't much, and lawyers can cost alot, so you'd need to be very sure of the outcome or you might wind up in the hole on this deal, worse than you already are.
Every city has some lawyer that advertises on tv that they will get you your rightful settlement when you have a wreck or something. Find out who it is, and if they will listen to your situation for free. If they will, you can find out what you need to know, and if there is any further money you can get out of this situation without paying any more than you already have.