Had a car dealership forge my name on a DMV document. Can I sue them?

Forgery is a crime, and the local prosecutor may be interested in prosecuting if you want to press charges.  For a civil suit of this type, however, you must be able to show damages.  Thus, for example, if they forged your signature on a contract, you can sue to invalidate the contract.  However, if the forgery did not cause you damage, for example if your name was forged on a document claiming that you are the new owner of a vehicle, which is true even though you didn't sign the document, you would not have a civil claim.