The Rolls-Royce Silver Ghost, also known as the 40/50HP, was a series of luxury cars introduced in 1906. This series of cars were first known as the 40/50HP, with one example being named the Silver Ghost. The name caught on, and soon all 40/50HP cars were known as Silver Ghosts. The Silver Ghost was powered by a 7.0L or 7.5L inline six, and was in production until 1926.