Praise be to Allaah.
If the sale has been completed and you have taken possession
of the car, then you may dispose of it, but you have to take it out of the
place where it was sold to you, to your place, or to some other place, or to
another showroom, so that you will have taken possession of it, because the
Messenger (peace and blessings of Allaah be upon him) forbade selling
goods where they were bought, until the merchants took them to their own place. That applies even if the rest of the procedures have not yet been completed, so long as the transaction between you two has been completed. Once you part, then the sale becomes binding. End quote.
Majmoo’ Fataawa Ibn Baaz (19/30).