In 1966 the Jaguar Mk X became the 420G as part of the revised range of Jaguar saloons. Essentially the 420G was a renamed Mk X 4.2 and could only be distinguished by an additional waist moulding and new badges.
As with the Mk X the 420G offered an immense bodyshell and was often used for chauffeur driven work, a divided limousine body was available although only a handful were built. After the models demise in 1970 the 420G platform continued to be used as the basis for the Daimler Limousine series, which continued in production until 1992.
Further information submitted:
8:1 compression ratio gave a (claimed) 250 BHP. 9:1 gave (claimed) 265BHP. The difference was brought about by domed pistons for the 9:1 version, similar to the E-Type.