汽车登记为物权登记，系生效要件主义，但登记薄的公信力只保护善意第三人，不能直接拿来作为承担交通事故责任的依据。在交易安全方面，应追求形式，坚持登记对第三人的公信力。在事故责任方面，应追求实质，坚持“运行支配和运行利益”理论，探讨真实权利主体及责任主体。 Registration of motor vehicles is a real property registration. However, the credibility of the register only protects the third-party who is goodwill and can not directly use it as a basis for assuming the responsibility for traffic accidents. In terms of transaction security, we should pursue the form and insist on registering the credibility of the third party. In the aspect of accident liability, the essence should be pursued, and the theory of “running dominant and operating interests” should be adhered to and the subject of real rights and the subject of responsibility should be explored.