The 6-cylinder XK engine was fitted to Jaguars for around 30 years - from the mid 1950s to the mid 80s - including the Mk 7, D-Type, E-Type and XK150. It still ranks as one of the most famous British engines and has been used as the power plant in a number of specials and kit cars. It is estimated that at the end of production something like 700,000 units had been manufactured.