Get a loan with your own bank. Theyll approve you for a certain amount. When you go to the dealer haggle . I recommend haggle enough so that the price is a good amount less than what your loan approval is for.

For example you get approved for 10k. The dealer is trying to sell you a car for 9k. Tell them something along the lines of ‘I can only go up to 8.5k. They’ll surely agree to that cause they also use a similar method as you except they try to increase the price and see what takes, while you are trying to decrease it if that makes any sense.