1. Negotiate with the car salesman: try to communicate with the car salesman and ask him to return his ID card, and explain the situation and requirements.
2. Consult the bank's handling method: If there is any loan problem, you can consult the corresponding bank's handling method and provide relevant evidence and materials to safeguard your rights and interests.
3. Alarm handling: If the car seller is found to be fraudulent, he can report the case to the public security organ and provide relevant evidence and materials to investigate his legal responsibility.