Banks and auto credit unions have some of the most competitive rates for all funding. Unlike going through a dealer, there is a little push to use them. The main disadvantage is the communication with the dealer and yourself. Banks have some of the most competitive rates for all funding. Unlike going through a dealer, there is the little push to use them. The main disadvantage is the communication with the dealer and yourself. Communicate with the bank or credit union, before and after the sale to the loan approved. Read More..