After 19 years' production, the 40/50hp Silver Ghost model, 'the best car in the world, was replaced by the 'New Rolls-Royce Phantom'. By this time Rolls-Royce was up against strong competition, and the new model had to exceed the standard of refinement already set. The company opted for an overhead valve and longer stroke engine of 7,668cc, this time using a single detachable cylinder head over two cylinder blocs. With the use of Rolls-Royce's own very effective twin-jet carburrettor, power was increased from 70bhp to 100bhp, a 44% increase over the Silver Ghost. Available in either 12' or 12'6'' long wheelbase, the ladder chassis followed the same principles as that of the Silver Ghost, while suspension was by semi-elliptic front and cantilever rear springs. With almost three tons of machinery capable of 80mph, faster than most cars of the day, greatly improved braking efficiency was achieved via power-assisted brakes operating on all four wheels using Rolls-Royce's own transmission powered servo, made under licence from Hispano Suiza, but also featuring operation while in reverse gear. Soon after 'The Autocar' reported that 'the much improved acceleration and maximum speed of 80mph has not been brought about at the expense of the traditional Rolls-Royce silence and smoothness'.