The Jaguar XJ was a series of cars built by the famous British manufacturers, which included classics such as the Jaguar XJ6 and the XJ12. Essentially regarded as luxury saloon cars, the XJ series was originally launched in 1968, the first model being the last to receive input from the company's founder, Sir William Lyons.

The Jaguar XJ6 was actually produced to effectively replace the entire range of saloon cars that were being produced by the Jaguar company in the sixties. The car featured either a 2.8 litre or a 4.2 litre, straight six XK engine and a version of Jaguar's renowned IRS unit.

Introduced in 1968, the Jaguar XJ6 had extras, which for the time were considered as the height of luxury; extras such as power-steering and leather upholstery and, in the 4.2 litre model, complete air-conditioning. However, an even more luxurious, up-market version was produced that was actually marketed with the branding of the Daimler Sovereign.

The XJ6 was to include some unique features such as the twin petrol tanks, which were situated either side of the boot. In 1972 a slightly elongated version of the car was produced that provided significantly more leg-room for back passengers and the existing model 8 transmission designed by Borg-Warner was replaced by a newly designed, model 12 unit. The addition of the new transmission improved the cars performance significantly.

Between 1968 and 1973 almost 80,000 XJ6s were made while the 4.2 litre version proved by far the most popular with almost 60,000 of these being produced. In 1973 however, the series II version arrived. Unfortunately, the series II, which was produced until 1979, has subsequently become synonymous with a 'poor-build quality' that was said to be partly due to Jaguar's incorporation into British Leyland and partly due to the labour union problems that so affected most of industrial England in the seventies. A total of 61,441 series II models were produced, while almost 10,000 coupe versions were made during the same period.

In 1979 the XJ6 was redesigned again and was produced under the title of the 'Series III'. Some 132,952 of these were produced until production stopped in 1992. From this time onwards several versions of what was essentially the Jaguar XJ6 were produced while they are better known for their alternative titles which include the XJ40, X300, X308, X350 and the X358. The latest model, which is still in production, is known as the XJ351.