What is the ruling on buying a car through an intermediary between the buyer and the seller on an installment basis, according to the amount of money paid upfront?

Question:
He says: Honorable Shaykh, may Allah grant you success. A type of sale has become widespread in some countries. When buying a car from a merchant or a wealthy person who has money, on an installment basis, the merchant asks the buyer how much he will pay upfront. Then he calculates the price based on the upfront payment. Usually, he makes the remaining amount double the upfront payment. For example, if he pays fifty thousand upfront, the remaining fifty thousand makes the total one hundred thousand, to be paid over several months. This merchant does not own the car; rather, he goes to buy it after the agreement is reached.

Answer:
This sale has two impediments. The first impediment is that the price is unknown. The price is unknown because it depends on knowing the upfront payment, and the upfront payment is unknown. The second impediment is that he sold something he does not own, but he goes to buy it and deliver it to the buyer. It has been stated previously that this is not permissible. One of the conditions for the validity of a sale is that the seller must own the item being sold at the time of the contract. As for owning it after the contract, that is not permissible. Yes.