You cant expect to pay off a car when selling it after owing it for a year. Even with low miles, and good condition they can't just give you all kinds of money for it. Trade it in on a brand new car and you would most likely be rolling in a loss.
You have to realize that this type of vehicle isn't flying off the lots either. They have to weigh out what its worth, and what they can sell it for.
Just because some website says its worth $XX.XX, doesn't mean that's even what its worth. ITS ONLY WORTH WHAT SOMEONE WILL PAY FOR IT.
A little while back EG sold a couple used (demo) STI's out of the dealership. Both loaded, one with BBS wheels, both with crazy low miles (under 2,000) and I'm pretty sure they sold for less then you owe on yours.