The Jaguar XJ is a saloon (or sedan) produced by Jaguar, launched in 1968. It was the last Jaguar saloon to have had the input of Sir William Lyons, the company's founder.

The brand-new X350 began production in the Spring of 2003 and as a 2003 model in Europe and as a 2004 model for the North American market. The X350 has an all-new aluminum structure and bodyshell. Steel is used in some places throughout the chassis. Aluminum underbody components are fastened together with aerospace-grade epoxy adhesives and around 3,200 self-piercing rivets to create the new XJ's unibody. The top-line XJs are branded as Vanden Plas (in North America) and Daimler (everywhere else). Two of the things that distinguish the X350 from previous XJ models include the outer headlights which are larger than the inner headlights and the wheels are pushed closer to the corners, both like the original XJ. Also, the X350 has a curve in its rear door like that of Jaguar saloons of the 1950s and 1960s.

The Super V8 is the fastest and most expensive model, with the XJR a close second. The Super V8, which debuted in the 2004 model year in the new X350 body style, is essentially a long-wheelbase, supercharged XJ8. Its primary competitor is the Mercedes-Benz S55 AMG. A distinctive wire mesh grille and chrome-finished side mirrors set the Super V8 and the XJR apart from the less expensive XJ sedans.

All North American XJs are powered by a 300 hp (224 kW) naturally aspirated engine. A 400 hp (298 kW) supercharged from 4.2 L V8 engine is optional. The valvetrain has a dual overhead cam design with four valves per cylinder. The top speed is limited electronically.

In early 2005, Jaguar announced its most exclusive, powerful and expensive XJ sedan since it ceased V12 production. Called the 2006 Super V8 Portfolio, it is a limited-edition trim level of the flagship Super V8 sedan. It debuted at the New York International Auto Show in March 2005, and is the most expensive Jaguar sedan produced to date, with a base price of US$115,995. The equivalent model is sold under the name Daimler Super Eight and Daimler brand on the European and other international markets.

The Super V8 Portfolio is powered by Jaguar's supercharged 400 hp, 4.2 L, 32-valve, AJ-V8 engine. Top speed is 155 mph and the Portfolio has a 0 to 60 mph acceleration time of five seconds.