I assume from the wording of your fact pattern that the car is no longer under it's manufacturers warranty. Assuming this to be true, and that you purchased this vehicle "as is" does not however allow the seller of a used automobile to commit fraud or make misrepresentations in order to deceive a buyer into buying one of their used vehicles.
Make a demand for the dealer to pay for the repairs.
If that does not work, hire a lemon law attorney.
Please be advised that the advice provided does not create any attorney/client relationship; that due to the various state laws that the information provided is a general overview of work comp law, which might not be applicable to you, based upon the laws of your state. We will not file anything on your behalf nor protect any statute of limitations which might arise and recommend that you IMMEDIATELY consult legal counsel for advice.