Well, its a GT with Nav, so it likely was MSRP'd new at 27k. So, the question is, has the car only depreciated 7k? I'd say more, especially with the fact that you can get a new 2008.5 or 2009 GT (without nav) for around 23, before taxes and other fees. Furthermore, you have more warranty, and better financing.
Best of luck!
Best of luck!