The Rolls-Royce 15 hp was one of four cars to be produced as a result of an agreement of 23 December 1904 between Charles Rolls and Henry Royce.[2] Badged as a Rolls-Royce,[3] the 15 hp was produced by Royce's company, Royce Ltd., at its factory in Cooke Street, Hulme, Manchester. It was sold exclusively by Rolls' motor dealership, C.S.Rolls & Co., at a price of GBP500.[1][4] The 15 hp was exhibited at the Paris Salon in December 1904, along with the 10 hp, 20 hp and engine for the 30 hp models, but as the new three-cylinder engine was not ready the chassis was incomplete.
Three-cylinder engines were quite popular in the early years of motoring, and one was part of the ambitious programme of the new company. The layout produced less vibration than