Well, the obvious first step is to contact the credit bureau which is reporting the "hard pull" on your credit and inform them that you did not authorize the inquiry. As with any other credit dispute, the bureau should then contact the dealer(s) and require them to show proof of your authorization for those inquiries.
Be careful, though. My guess is that somewhere along the line, the dealer (maybe in very tiny writing somewhere) got you to agree to an inquiry without actually coming out and saying that's what they were going to do, in which case you may have to go to a different step.
It seems to me that state and/or federal laws prohibit the practice of pulling your credit without express consent, in which case you could have grounds for civil action against the dealer(s). There may also be criminal laws which have been broken. Here's an article from CreditCards.com about this very subject, and it might be a worthwhile read for you.
Here's an article from NoLo.com about impermissible use of credit inquiries that's very interesting.
If, as you state, this was done without your consent then there are PLENTY of legal remedies at your disposal. Just be certain beforehand that you know without doubt you did not authorize the inquiries, and you should prevail.
I hope this helps.