The idea of a mid-engined prototype was first mooted in 1960, but it was not until 1965 that construction began, with the first car running by March 1966. The aluminium body was designed by Malcolm Sayer, the aerodynamicist responsible for the Jaguar C-type, D-type, E-type and XJS, who used his Bristol Aeroplane Company background to build it using techniques borrowed from the aircraft industry.
William Heynes recognised as early as 1964 that a car such as the XJ13 needed an experienced race driver to help develop it. Jack Brabham was approached in this regard but the challenge was eventually taken up by ex-Jaguar Apprentice David Hobbs. David Hobbs was recruited as the XJ13's main test driver. In 1969 Hobbs was included in a FIA list of 27 drivers who were rated the best in the world. Hobbs achieved an unofficial UK closed lap record with the XJ13 which stood for 32 years. The XJ13’s main test and development driver, Hobbs, was joined at Silverstone for the XJ13’s final test at full racing speed by another racing driver (and ex-Jaguar apprentice) Richard Attwood.