When is a good time to refinance a car loan?

Refinancing is worth checking when your credit score has meaningfully improved, market rates have dropped, or your original rate was high. It's usually most valuable early in the loan, when more of each payment goes to interest. Many lenders want you to have made several on-time payments first. Compare the total remaining cost of your current loan with the new offer, including any fees, to make sure you actually come out ahead.