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Engine design was shared between the aircraft and cars... one crankshaft was carved from a 700 lb billet steel block. Consider that the types of engines in the 30's were huge displacement and fewer cylinders, like a 487 cu in straight 6 cyl... and that Hispano Suiza had aluminum cylinder block and overhead camshafts at a time when Rolls-Royce's venerable Silver Ghost was still using side valves, and an iron block cast in several pieces.
It was also ahead of Rolls-Royce in the braking department. While the Rolls had brakes on the rear wheels only, the Hispano had four-wheel brakes, servo assisted by a shaft driven off the rear of the transmission. Rolls-Royce later adopted this system under licence from Hispano and used it for many years.
http://www.thoroughbred-cars.com/cars/france/hispano%20suiza/Hispano%20Suiza%20H6C.htm