The XJ series comprises six models, all built on a platform that makes extensive use of lightweight but strong aluminum architecture. Three XJs are powered by 4.2-liter V8 engines. The XJR and Super V8 models are supercharged. The XJ8 and XJR are built on the standard 119.4-inch wheelbase. The XJ8L, Vanden Plas, and Super 8 are built on a longer 124.4-inch wheelbase that stretches the overall length of the vehicle from the standard 200.4 inches to 205.3 inches. Safety features that come standard on all models include frontal, side-impact and side-curtain airbags, antilock brakes and electronic stability control.For 2006, The Jaguar XJ comes in a new limited-edition Super V8 Portfolio model. All XJ models also benefit from a number of upgrades, including more powerful engines, a new braking system, laminated glass for improved noise isolation, a driver-selectable automatic speed limiter, and a new tire pressure monitoring system. The chrome mesh grilles from the R models are now seen on all models, while new smoked-lens side markers and the removal of body-side and front/rear window moldings give all models a fresh appearance. A new navigation system comes standard on XJR and Vanden Plas models, and an electric rear sunblind is fitted to every XJ8 L.