Rolls-roycemotorcars.com:
In 1919, Rolls-Royce built 1EX, its first experimental car. Based on a Silver Ghost chassis, it was used as a rolling test bed to develop ideas and engineering solutions that would be incorporated into later generations of production Rolls-Royce cars.
A succession of EX cars followed over the next 40 years, culminating in the 45EX of 1958. Many notable cars were produced in that time, including the 15, 16 and 17EX cars of 1927, which were based on the original Phantom’s chassis and given to three prominent coachbuilders: Hooper, Barker and Jarvis. These eminent companies then engaged in a competitive challenge to create their own unique interpretation of a sporting, lightweight version of the Phantom. Such drive and determination is the very essence of EX.