Special finance rate terms may be restricted to certain models and are more likely to be offered on new cars. So if a dealer is promoting low-rate financing, you have to be sure it's available on the specific vehicle you want. Also, make sure the rate will actually be given to a person with your credit score and history. Finally, you also need to know if that rate affects the purchase price. That's why many used-car shoppers prefer to separate the financing from the purchase and get their car loan from  Affinity.