coming from Autoblog too. Registered just to post this.
I would say get a lawyer, if you don't have one yet. Don't listen to their lawyer, he is just trying to scare you. Once you have your lawyer contact them, they will back off. There is absolutely nothing illegal in what you are posting on the websites, you are free to express your opinion about someone or something. Even if you sue them, it won't get to court. It will be settled before that.
Get a lawyer. Contact Hyundai of America. While it won't exactly lead you to getting a free car, this will put a big dent on them since they are the ones approving their dealerships. Put the media on it, CNN loves stories like that.
But whatever you do, DO NOT listen to their lawyer. They have no legal stand in this chaos, absolutely none. You won it, they are under legal agreement to sell it. You didn't bid on a pencil, you bid and won a car auction. They see that you probably have no lawyer, so they are just trying to scare you off. My serious recommendation, get a lawyer. Explain the situation to him/her.
Spread it among as many sites as you can, nobody wants bad rep. And stories like that usually turn out in favor of the buyer, ones media and websites are involved.