The Rolls-Royce Silver Ghost was originally introduced as the 40/50 hp.
Rolls-Royce launched the 40/50 hp chassis in 1906 as a large, powerful model positioned above the company's earlier cars. The designation referred to its taxation and engineering classification rather than a straightforward modern horsepower rating. A particular 40/50 hp car, chassis number 60551, received the name Silver Ghost and made the nickname famous.
The Silver Ghost name became associated with the entire 40/50 hp range, especially after the car's celebrated reliability demonstrations and long-distance trials. Rolls-Royce later used the name in a broader historical sense, which can make the original technical designation easy to overlook.
The model was not the company's first car and was not originally sold under the Silver Ghost name. That distinction matters: “40/50 hp” identifies the model series at introduction, while “Silver Ghost” began as the name of a particular car and later became the familiar name for the series.