Depending on the reason you're refinancing in the first place, you could pay higher interest than you have on your current loan. For example, if you need more time to repay the loan and refinance it for a longer term, you'll end up paying more interest, even if the rate is lower. Another advantage of refinancing is the ability to make car payments more manageable. If your finances are a little tight right now, refinancing while market rates are low can lower your monthly payments by reducing interests.
You can pay refinancing fees. Auto refinancing can include a variety of costs, including application, origination, and title transfer fees. However, not all lenders charge the same fees, and some may not charge any. When comparing refinancing options, read the fine print and consider all associated charges.
In the end, paying too much to refinance your car loan could cost more than maintaining your current loan. Longer loan terms give you more cash in the moment, but they can be problematic. You'll have to pay more interest over the life of the loan, and some borrowers are too comfortable with extending their loans. You may end up paying much more for the loan if you extend it on an ongoing basis instead of paying according to the current schedule.