The 1920s – Rolls-Royce 20 H.P. the ‘Twenty’.

Henry Royce was getting ready for a post-war world that he knew would be drastically altered even before the Armistice was signed in 1918. He reasoned that some customers would no longer be able or willing to operate the marque's most popular pre-1914 model, the 40/50 H.P. "Silver Ghost," since it would likely be impossible to find, hire, or finance a mechanic or chauffeur as they had done in the past. He had to design an automobile that was easier to maintain and, more critically, that the owner could operate on their own. Simultaneously, Royce understood that these discriminating customers would not settle for anything less than the legendary Rolls-Royce standards of perfection, and he would not either.

The 20 H.P., Rolls-Royce's first "small horsepower" vehicle ever created with owner-drive capability instead of chauffeur assistance, was presented on October 6, 1922. It was evident right away that the "Twenty," as it soon became known, was a significant advancement in technology. Its 3.1-litre, straight-six cylinder engine was less than half the size of the 7.5-litre engine in the Silver Ghost, but it also weighed around 30% less. This indicated that there was far less of a performance disparity between them than the raw data would imply. In fact, the "Twenty" made the Silver Ghost appear somewhat antiquated with its lighter controls and more sophisticated brakes, suspension, and steering systems; that being said, the bigger model was still far superior to its immediate rivals.

The "Twenty" swiftly established itself as a solid favourite with both long-time Rolls-Royce owners and recent buyers, for whom, as Royce had anticipated, acquisition price and continuing operating expenses were more significant factors than they had been a few years prior.

In letters to the motoring press, one happy owner praised it as ‘a charming piece of mechanism’ while another declared, ‘I have never handled anything as sweet-running’. A company advertisement quoted an expert assessment of the car as ‘everything a motorist can want… motoring with a high degree of refinement and its simplicity of construction will delight the driver’. After taking delivery of his car, a contented customer wrote to the company from his home in France, declaring, ‘I drove my 20 HP here from Liverpool and am very satisfied with the running of the engine, not having to change gear between Liverpool and Versailles’.

The "Twenty," like all other Rolls-Royce vehicles of the time, was built as a "rolling chassis," on which owners hired a private coachbuilder to create custom bodywork. Royce's main objective has always been for the owner to drive the car, and the company assumed that both customers and coachbuilders would accept this by designing their cars to be as light and svelte as possible.

He was not, however, able to alter some clients' ingrained patterns. Numerous proprietors continued to insist on defining their preferred design of substantial, formal coachwork, which was heavier and resulted in increased wind resistance. Royce was understandably dissatisfied with the way these large, overbuilt bodies ultimately hindered performance.

As a practical person, Royce was aware that there was only one approach to raising the weight-to-performance ratio. The 20/25 horsepower, which had an expanded capacity engine, replaced the 'Twenty' in 1929. The 25/30 horsepower, which had a 4.25-litre powertrain, followed in 1935. The 1938 Wraith was the penultimate vehicle to come from the "small horsepower" period. These subsequent incarnations, which are all direct extensions of the "Twenty," enhance the record and renown of the original.

Even after the manufacture of the "Twenty" ended in 1929—by which point there had been no fewer than 2,940 built—it continued to have a significant impact on Rolls-Royce. Specifically, the straight six-cylinder engine, which had overhead valves and a removable cylinder head, would serve as the model for Rolls-Royce engines for many years to come. Even though the Silver Cloud model (1955–1959) had several internal advancements, the shared history of all six-cylinder Rolls-Royce models is evident when you open their bonnets. Additionally, the engine of the new Phantom, which took the place of the old Silver Ghost in 1925, also embraced the crucial "Twenty" design.