Dealers often arrange loans through lenders they partner with, and the rate they offer isn't always the best one you could qualify for. If you don't have another option in hand, it's hard to know whether the deal in front of you is a good one.

Before you shop, check your credit report for errors and apply for preapproval with a bank or credit union, or with more than one lender. Preapproval gives you a clear idea of the rate and loan amount you qualify for, which helps set your budget. Many lenders treat several auto loan applications within a short window as a single inquiry for scoring purposes, but ask to be sure.

At the dealership, you can mention that you already have financing and ask whether they can beat it. Sometimes they can, and sometimes not. Either way, you'll be comparing real offers rather than guessing. Read the full loan terms before you sign, including the length of the loan and any fees.