For lowering interest rates: If you come across a new/refinancing loan option at a lower interest rate during the course of your existing car loan, you can choose this new option and lower the overall interest that you pay on your loan. All you have to do is pay off your current loan and approach the new lender. However, you should make sure that the prepayment penalty charged for your old auto loan is lower than the benefits offered by refinancing.You can also consider refinancing your car loan if your credit score has improved over your loan tenure. When this happens, you may be eligible for a finer loan deal at a lower interest rate with better terms.