The Bentley S1 and Rolls-Royce Silver Cloud 1 were manufactured between 1955 and 1959. The cars were identical, featuring the Rolls-Royce 4,9L straight-six engine. Autocar wrote after test-driving a Bentley S1: "The interior is utterly silent at 100mph when the windows are closed. One is conscious of the speed only by watching the speedometer or the rapid approach of the horizon. The occupants of the car converse in drawing-room tones, marveling at the almost eerie silence."