The Rolls-Royce 10 hp was the first car to be produced as a result of an agreement of 23 December 1904 between Charles Rolls and Henry Royce,[1] and badged as a Rolls-Royce.[2] The 10 hp was produced by Royce's company, Royce Ltd., at its factory in Cooke Street, Hulme, Manchester, and was sold exclusively by Rolls' motor dealership, C.S.Rolls & Co., at a price of £395. The 10 hp was exhibited at the Paris Salon in December 1904, along with 15 hp and 20 hp cars and engine for the 30 hp models.
The 10 hp was a development of Henry Royce's first car, the Royce 10, of which he produced three prototypes in 1903. This was itself based on a second-hand Decauville owned by Royce which he correctly believed he could improve. In particular, Royce succeeded in making his car significantly quieter than existing cars. Unlike the Royce 10 which had a flat-topped radiator, the Rolls-Royce 10 hp featured one with a triangular top which would appear on all subsequent cars.
The engine is a water-cooled twin-cylinder of 1800 cc enlarged to 1995 cc on later cars, with overhead inlet and side exhaust valves,