Is it permissible to sell a car whose ownership has not been transferred and which has not been inspected, then sell it again without inspection, or does this fall under selling what one does not own?

Among the conditions for a valid sale is that the item being sold must be known to both contracting parties, either by sight or by a description that takes the place of sight in distinguishing it. So, if it is a car, it is necessary to know its type, year of manufacture, color, services, advantages, and defects. If this is not done, the sale is invalid. If the sale is concluded through offer and acceptance, ownership of the sold item transfers to the buyer upon taking possession of the goods. The registration process is merely a documentation and confirmation, and the lack of registration does not affect the validity of the sale.