You can't just opt out of a contract. In the fine print of the contract you will find that the bank does not guarantee the product. They are giving you financing. The conditionof the product is between you and the dealer. Go through all of your paperwork. You should have signed a document that either said, "No warranty, as is" or it may have provided for a limited warranty(perhaps 90 days). When you buy a used vehicle, it is to be expected that their may be some problems. Presumably the price you paid should have reflected the condition of the vehicle. A reputable dealer should not have sold a vehicle in this condition, however there is no requirement to provide you with a list of things wrong with the vehicle. The burden was on you to have the vehicle checked out, or to at least get a limited warranty.