How can i (legally) get the word out about a local unethical ripoff artist car dealer?:
Ok. You have to be careful on how you play your game here because if he can prove that anything you say about him is untrue he may have grounds for his deformation suit.

If he has wronged you, there are a couple of things you can do:
1. Sue him for the wrong he did to you. 
2. Contact the better business bureau in your area
3. Report what he did to the government group that regulates car dealers in your area
4. Contact the TV station in your area that does customer complaint reporting.