Don't wait until you're in the dealership office to figure out financing. While it makes sense to get a quote for a dealer car loan, you can search for better financing through a bank or credit union, which are 1 to 2 percent lower than conventional banks.
There are now many community credit unions open to anyone living in their area, eliminating the need to work at a certain company to join. With credit loosening, blank-check auto loans, or prearranged financing ... are being offered more widely, which will allow you to negotiate without wondering about your interest rate.
For a quick comparison, use Bankrate.com's rate search tool on auto loans to see current interest rates nationwide.