Why do I need my real estate license photo or social security to buy a car in Shanghai?

This is a normal routine. How can I put it? The price concessions of the same car are different in every city or even in every store at the same time. The purpose is to stabilize sales in second-and third-tier cities, so you must have a residence permit or social security certificate to prove that you live in this city. If it is a foreign brand, some stores still need a service fee of 3,000 yuan, which is actually a deposit. Where can I register my license plate when I buy a car and get a refund after I get it? In short, the water is deep and you can't figure it out.