Car Evolution: Jaguar XJ in Detail

Page 1: Overview
Page 2: Design
Page 3: Engine/Safety
Page 4: XJ Heritage

THE POWER TO SUPPORT THE LUXURY

For 2006, all XJ models get more power, together with the added benefit of reduced exhaust emissions. The naturally aspirated version of the 4.2-liter V8 produces 300bhp SAE (up from 294bhp) at 6,000 rev/min, again with impressive mid-range flexibility and with a torque peak of 310 lb.- ft. SAE at 4,100 rpm.

Against the clock, this engine can accelerate the XJ from standstill to 60 mph in just 6.3 seconds, while averaging 18/27 mpg city/highway. However, paired with the advanced lightweight aluminum construction, it is also an engine that provides class-leading fuel economy.

The mechanically supercharged 4.2-liter V8 uses an Eaton supercharger, twin high efficiency intercoolers, a special twin pump fuel system, and forged oil cooled pistons to handle the increased internal loads and temperatures without compromising durability. It produces a very strong 400bhp SAE (up from 390bhp) at 6,100 rpm, and a robust torque peak of 413 lb.-ft. SAE at only 3,500 rpm. What's more, its exceptional torque spread delivers at least 86 percent of the peak torque figure across a very wide range, from 2,000 rpm to well beyond the peak point. Against the clock, it delivers 0- 60 mph sprinting in just 5.0 seconds.

Both engines share similar construction, with aluminum alloy blocks and cylinder heads, designed for high strength, long durability and minimum transmitted noise and vibration. All use chain driven overhead camshafts with low noise, fine pitch, inverted tooth chains and sprockets. For 2006, supercharged as well as naturally aspirated engines use Variable Camshaft Phasing (VCP), continuously varying the phasing of the inlet camshaft according to demand, to optimize low speed torque and high speed power, while reducing emissions. High compression ratios and multi-hole injection nozzles improve combustion, improving fuel economy and further reducing emissions. Short engine and catalyst warm up times make further gains.

The XJ continues to offer the choice of powerful, refined and efficient V8 engines both matched to the advanced ZF six-speed automatic transmission that was the world's first stepped six-speed automatic transmission when it made its debut in the S-TYPE in 2002. This light, compact unit is perfectly matched to the V8 family's power characteristics, and is also a major contributor to the XJ's refinement. It features Bosch Mechatronic shift � an electro-hydraulic shift mechanism incorporated into the main gearbox casing and whose adaptive shift strategy (controlled by the ECU) responds both to road conditions and to the way the car is being driven � to give the smoothest shifts and optimum performance. It also uses the latest version of Jaguar's 'J Gate' selector, for smooth shift action.

With only a minimal weight increase for the long wheelbase XJs over the standard wheelbase XJs, all derivatives have virtually unchanged levels of performance. Engine recalibrations also see the naturally aspirated AJ-V8 move from its previous LEV2 low-emissions rating to ultra low emissions ULEV, while the supercharged AJ-V8, which gets variable cam phasing for 2006, improves from LEV to LEV2 classification.

DRIVING DYNAMICS - STILL THE XJ WAY

For the 2006 model year, all XJs feature a new braking system designed by Teves. The Teves system is designed to give improved performance and pedal feel with more initial �bite�.

On all naturally aspirated XJs � the XJ8, XJ8 L and Vanden Plas � the diameter of the front rotors increases from 12.6 inches to 12.8 inches, while the rear rotors increase in diameter from 11.3 inches to 11.8 inches. On supercharged models, a new Conti-Teves R Performance system is incorporated featuring new ventilated 14.0-inch front rotors and12.8-inch rears. The previous cast aluminum calipers have also been switched to an aluminum/cast iron composite to give improved caliper stiffness and deliver even better high-speed braking performance.

All XJ models still feature four-channel Anti-Locking Brakes (ABS) and Emergency Brake Assist (EBA), which contribute to the Traction Control and Dynamic Stability Control (DSC) systems. Traction Control combines engine torque control, to reduce engine torque, and selective rear wheel braking using the ABS system, to counteract wheelspin when too much power is applied on a low grip surface. DSC uses engine torque control plus selective braking on all four wheels to counteract either understeer or oversteer if the limits of adhesion are overstepped.

The combination of Jaguar's industry-leading Computer Active Technology Suspension (CATS) and the double wishbone layout and air springs ensures the classic Jaguar balance of agile handling, outstanding ride comfort and fine steering feel. CATS is an electronic control system that operates by continuously adjusting the damping characteristics to suit the driving conditions � optimizing both ride and handling. These adjustments are seamlessly made by the electronic control unit (ECU) which receives input from a series of sensors.

Both front and rear suspensions are mounted on isolated subframes, with rubber and hydraulic bushes to give precise control with maximum noise and vibration suppression. Pressurized air springs are used rather than conventional steel coils to give ample travel while optimizing the balance between comfort and control. Effective spring stiffness increases with load, to give a consistent ride, and ride height is automatically controlled according to the data supplied by three height sensors. At high cruising speeds, ride height is automatically lowered by 0.6 inches to enhance stability, minimize aerodynamic drag and maximize fuel economy.

Dynamically, the XJ long wheelbase is uniquely distinguishable from the standard wheelbase car. While gaining interior space it remains compact enough to fit into an average-sized garage, and to handle the tight spaces of multi-level parking structures. Its turning circle is a tight 39.5 feet that out-maneuvers the competition. Even with the additional five inches, the aluminum alloy monocoque shell retains its exceptional stiffness and light weight allowing the long wheelbase models to have the same highly-acclaimed ride, handling balance and steering feel as the standard wheelbase model.

SAFETY

The target in developing the aluminum-intensive XJ was to produce one of the world�s safest cars.

Building on the solid active safety foundations of excellent handling, road-holding, braking and stability, the XJ is equipped with Jaguar's Adaptive Restraint Technology System (A.R.T.S.). This system employs the world's most comprehensive and sophisticated sensing technologies to monitor the position of the front passenger, while other sensors detect the passenger's weight, the position of the driver in relation to the steering wheel and the usage - or not - of safety belts. A.R.T.S. has the capability to sense the severity of a collision and deploy the vehicle's passive safety system.

All 2006 XJs are also equipped with an advanced tire pressure monitoring system to enhance vehicle safety, and provide extra peace of mind for driver and passengers. Unlike some other systems, which use a car�s anti-lock brake sensors to detect drops in tire pressure, Jaguar�s system uses radio frequency transmitters. This allows each tire � including the spare � to be accurately and precisely monitored. And, unlike the ABS-based systems, it can detect if all four tires lose pressure gradually. If the pressure in any of the five tires drops by 25 per cent of the recommended threshold, a warning light on the instrument cluster flashes.

The new laminated side glass on the 2006 XJs aids in safety as well as reduces interior noise levels even further. Featuring two layers of laminated glass separated by an ultra-thin acoustic interlayer, the laminated side glass makes �smash and grab� thefts more difficult. The plastic interlay between the glass also reduces harmful UV rays, which can deteriorate interior trim.

Earlier this year, Bluetooth � wireless technology for mobile phones became available on all Jaguars, including the XJ. With the optional Bluetooth � wireless module installed, an owner�s compatible Bluetooth � capable cell phone automatically links with the car�s system, allowing safe, easy, hands-free cell phone operation.

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