The exact amount that you will pay for Car Finance depends on your circumstances. Your down payment, the length of your repayment and any additional charges your lender adds will all change what you pay every month. Looking at our Car Finance Calculator, a £15,000 loan paid back over 36 months at 6.9% APR will cost just over £461 a month. Change that to a 48 month repayment and this goes down to £357, though the finance costs you more over time.