Thanks everyone for you help, I went to the traffic department myself this morning. That is correct, the new buyer has to be present with the seller as he is required to sign a document. He also needs a NOC from his company. In my case as I am leaving Qatar before the new buyer returns from vacation, the police have said that I can sign the document and leave it with the duty officer. On the return of the new buyer from vacation, he will just provide the NOC, produce all his QID, drivers license and the transfer will take place although I won't be in Qatar.
Thanks all
Putsie