Start with what the Rolls-Royce 30 hp is: a car with 6000cc 6-cylinder., built from 1905 to 1906, when a car was a rich man's adventure and every maker was a workshop. What it meant takes a little longer. The shape is credited to Sir Henry Royce.
The background
The Rolls-Royce 30 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. Badged as a Rolls-Royce, the 30 hp was produced during 1905 and 1906 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 GBP 890. The engine was exhibited at the Paris Salon in December 1904, along with the 10 hp, 15 hp and 20 hp models. Claude Johnson was keen that a six-cylinder model was included in the Rolls-Royce line-up as other "quality" makers, especially Napier, were adding them to their ranges. The 30 hp was discontinued when the company changed to a single model policy and launched the 40/50 (Silver Ghost).
The engineering
The engine is 6000cc 6-cylinder.. Drive goes through a four-speed. The wheelbase is 112 in or 118 in. These are manufacturer figures carried by Wikipedia and Wikidata, not road-test measurements.
Where it sits
In the Rolls-Royce line-up the Rolls-Royce 30 hp has a clear place: it handed the line to the 40/50 (Silver Ghost). The cars a buyer would have weighed it against include the Ford Model T, the Bugatti Type 8, the De Dion–Bouton Fouillaron type 10 HP tonneau. Its Rolls-Royce stablemates include the Rolls-Royce 100EX and the Rolls-Royce 102EX.
Owning one today
There is no federal ownership record for the Rolls-Royce 30 hp — it predates the complaint database or was never sold in the United States — so MotorJury publishes no running-cost figure for it. For a car of this age the price is set by the collector market and the condition of the individual example, not by a formula.