Interest rates: Like any loan, one of the most important things to consider about a used car loan is the interest rate. Used car loan interest rates are higher than that of new cars and can range from 10-17 per cent. On the other hand, interest rates on personal loans could range from 10.5- 22 percent. Also personal loans would help you fund the entire amount of the car. When going for a used car loan, find out the interest rates being offered by different banks and financial institutions. Also, compare it with personal loan interest rates before making a decision.