When users choose to use vehicles as collateral for loans, they usually need to hand over the green copy (vehicle registration certificate) to the lending institution for safekeeping. During the loan period, users cannot buy, sell or transfer vehicles, because the Green Paper is one of the necessary documents for vehicle trading and transfer. Users can only get back the green book after paying off the car loan. After getting the green book, users can trade and transfer the car freely. There is another option for car loan mortgage. This means that the vehicle is used as collateral, but the green copy is still kept by the user. In this case, the user can't use the vehicle during the loan period, because the lending institution needs to ensure the safety and integrity of the vehicle. Users need to weigh the pros and cons and choose the appropriate loan method according to their own needs and conditions.