Wallace, who will leave on June 30, joined as an accountant in 1975 and progressed to the board in 1985, having responsibility for the VW/Audi business. He became chief executive in 1991.
He presided over the establishment of the Audi centre in Hall Road, the acquisition of the Mercedes-Benz market area for East Anglia in 2002 and the development of the new Meridian Park Audi Centre in Norwich.
Other highlights were the acquisition of the Skoda franchise and the Lowestoft VW/Audi/Seat business last year.
Robinsons’ chairman Roger Robinson says: “Phil has always been a pleasure to work with. We all owe Phil a vote of thanks for the good care he has taken of the company.”