Jaguar XJ40. The group covers ownership and information on XJ6, Sovereign, Daimler, XJR and specialist conversions of the Jaguar XJ40 manufactured between 1986 and 1994. Everyone who owns or has an interest in the XJ40 is very welcome. XJ40 is the model code name used by Jaguar while the car was being developed and was officially marketed as the new XJ6, however as XJ6 was used on several different models of Jaguar the XJ40 moniker was adopted for ease of reference.