Legal analysis: the calculation formula of interest on second-hand car loans is: monthly payment × loan term-loan amount = total interest. At present, the minimum down payment for new car loans is 30% for three years, and the total interest is 12% to15% of the total loan amount; For a three-year loan for used cars, the minimum down payment is 50%, and the total interest exceeds 20% of the total loan. Precautions for buying used cars: unsecured loans for used cars. The age and mileage of a used car will determine whether it can be used as a mortgage. If the used car is too old, it is difficult to apply for a loan. Therefore, the age of the mortgaged used car applying for a loan cannot exceed 3 years.

Legal basis: Article 14 of the General Principles of Loans: Lenders and borrowers shall collect or pay interest on schedule in accordance with the loan contract and relevant interest-bearing provisions of the People's Bank of China. When the loan extension period and the original term reach the new interest rate term grade, the loan interest will be charged at the new term grade interest rate from the date of extension. Penalty interest is charged for overdue loans according to regulations.