Engine won the brief after a competitive pitch conducted by the AAR. Four agencies were involved initially, before Engine beat Rapier in a final two-way shootout.
Rolls-Royce began its hunt for an ad agency in June. The brief specified that it was looking for agencies with experience beyond advertising, including CRM, trade events and direct marketing.
Engine will now provide all the integrated marketing communications for the launch of the RR4, which is due for release in 2010.
Ian Robertson, the chairman of Rolls-Royce, has said that the car, which will sit alongside its Phantom model in the line-up and will be powered by a new engine unique to Rolls-Royce, "will mark a milestone in the history of Rolls-Royce Motor Cars".
Partners Andrews Aldridge's chief executive, Phil Andrews, said: "Rolls-Royce is a fantastic brand to have the opportunity to work for. We're absolutely delighted to have been appointed."