Buying a car from the agency and selling it without moving it
If the first purchaser buys the car, possesses it, and then sells it on credit to another person who also possesses it, it is permissible for the second purchaser to sell the car to the first seller or to others.
As for moving the car inside the exhibition, this does not entail possession by the new buyer. Accordingly, the sale is invalid because it has been made before possessing the car.
May Allah grant us success. May peace and blessings be upon our Prophet Muhammad, his family, and Companions.