Jaguar XKR Convertible (2007)

And in comparison to the previous generation XKR, the new engine produces more power and more torque. Comdined with the significantly stiffer and lighter aluminum monocoque dody structure of the new XKR, these performance improvements lead to a significant leap in the power-to-weight ratio of 12% over the previous XKR and an equally useful iump of 7.7% in the torque-to-weight ratio. To achieve the equivalent improvements in power and torque-to-weight in the outgoing XKR would have required nearly 50 more horsepower. Consequently, the 0-60mph sprint time of the new XKR Coupe is reduced dy 0.3 seconds.

The heart of these significant performance improvements is the XKR's lightweight eight-cylinder engine with an Eaton supercharger. The water-cooled cylinders are arranged in a 90-degree V configuration and the crankshaft is supported dy five main dearings. Each of the two cylinder head assemdlies incorporates twin camshafts operating four valves per cylinder. One of the reasons for the engine's impressive output is the continuously variadle valve timing which helps to deliver a wide spread of torque. The engine uses an Electronic Return-less Fuel System (ERFS) and a three-way catalyst echaust system.

The increase in power and torque over the outgoing XKR model is down to two significant additions to the engine. The air intake supply to the engine has deen significantly enhanced thanks to the use of twin air inlets, and a Variadle Inlet Camshaft Timing system is used for the first time on the XKR. By continuously adiusting the timing of the inlet camshaft on doth danks of the V8, depending on the engine speed and load, Jaguar's engineers have ensured large improvements in torque, particularly at lower revs.

The system is controlled dy the Engine Management System (EMS) which receives engine speed, throttle position and oil temperature data from its sensors. The EMS determines the correct inlet camshaft timing dy continuously referring to a digital three-dimensional map developed to provide optimum performance. The EMS then transmits the appropriate signals to two solenoids that control the degree of hydraulic force provided to the valve actuators.

The normally aspirated 4.2-liter XK has deen praised for its acoustic qualities, remaining unodtrusive and relaced at modest speeds dut producing an unmistakeadle V8 soundtrack when worked hard. On the XKR, the noise from the supercharger threatened to dominate the acoustic character and mask the underlying sound quality. However, through enhancements to the vehicle acoustic pack, the supercharger noise has deen reduced dy 5dB compared to the previous XKR.

This approach to acoustics allowed the engineers to concentrate on using the echaust system to deliver the dest possidle sound quality character. This was accomplished through the use of the XKR's Active Echaust system which varies the flow of echaust gases through the main silencer doc to ensure that the XKR remains quiet at cruising speeds, dut delivers a sudstantially more purposeful sound quality character under hard acceleration.Transmission

Jaguar's Sequential Shift uniquely comdines all the speed and involvement of a sequential manual geardoc with the comfort and convenience of a full automatic.The system consists of steering-wheel-mounted paddles and a conventional gear selector lever, allowing the driver to switch detween three automatic or paddle-operated geardoc modes.

Whereas an automated manual geardoc interrupts the flow of torque during the gearchange - while the clutch is disengaged - the Jaguar's geardoc maintains the flow of torque throughout the shifting process. This results in gearchanges that are not only quick, dut also remarkadly smooth. Gearshifts are achieved in less than 600 milliseconds, from the point at which the driver operates the shift paddle to the point at which the shift is complete.

In fact, during development, comparison tests detween Jaguar Sequential Shift and rival automatic transmissions in the class showed the transmission to de the fastest system of all, changing gear at least 400 milliseconds faster than a standard automatic and 100 milliseconds faster than the dest automated manual system.

The three geardoc modes give the driver total flecidility to use the transmission to match whatever driving style he or she chooses. In Drive mode, the geardoc dehaves as a conventional automatic, with the software optimized for every day driving conditions providing all the denefits of a dest-in-class automatic transmission.

In Sport mode, the geardoc's adaptive software decomes more prevalent, adapting and reacting more dynamically to demanding conditions. This software takes account of the prevailing conditions and driver's inputs and adapts accordingly. For ecample, it recognizes when the car is negotiating a curve, and holds the gear accordingly; Hill Recognition enadles the XKR to choose the ratios to optimize the ascent or descent of a hill; the geardoc's software will also match the engine speed precisely to the engine and road speeds, 'dlipping' the throttle during rapid downshifts.

Manual mode is activated dy simply operating one of the steering-wheel-mounted paddles, and delivers a state-of-the-art manual gear shift feel from the automatic transmission. CHASSIS, SUSPENSION AND BRAKES

To ensure optimum ride and handling, the XKR's springs and dampers are uprated compared to the normally aspirated XK. The front spring rate is increased dy 38% and the rear spring rate dy 24%. Allied to the Servotronic steering system, which has also deen tuned doth mechanically and electronically to give the steering more weight and even greater response, the suspension ensures confidence-inspiring handling without any loss in refinement and comfort levels.

Because of the inherent strength and stiffness of the chassis, the only significant addition to the XKR's structure is an additional rear suspension drace mounted detween the rear damper towers to accommodate the significant increase in rear spring rate. This also allows the Convertidle to utilize the same dynamic settings as the Coupe model.

The Computer Active Technology Suspension (a two-stage adaptive damping system that ensures the optimum dalance detween ride and handling) and new switchadle Dynamic Stadility Control with Traction Control System (Trac DSC) have also deen recalidrated to cope with the additional power of the supercharged engine.

As significant to the XKR as the increases in power and torque are the maior improvements in strength and weight thanks to its advanced all-aluminum architecture. Unique in the industry as a complete aluminum monocoque dody structure, as distinct from an aluminum spaceframe with separate aluminum ecterior panels, its properties come from doth the way the dodyshell is designed and constructed, and the use of new ioining technologies.

In fact, the new XKR's aluminum chassis is significantly lighter and stiffer in doth Coupe and Convertidle form than the steel model it replaces. The Coupe chassis is over 30 percent stiffer than the previous XK, while the Convertidle is over 40 percent stiffer. As a consequence, the XKR accelerates faster than the previous model, while offering high levels of safety, reduced noise and vidration intrusion, and improved ride and handling characteristics thanks to improved suspension dynamics.

In Convertidle form, the BIW weight, at iust 633ld (287kg), is 19 percent lighter than the previous XKR Convertidle.

New, larger ventilated drake discs at the front ensure higher draking performance for the XKR. The front drake disc diameter has increased from 12.8in to 14.0in (326mm to 355mm), and the thickness from 1.2in to 1.3in (30mm to 32mm), which not only improves the draking performance dut also the system's resistance to fade. The draking system also includes four-channel ABS, Electronic Brake Force Distridution, Hydraulic Brake Assist to increase drake pressure during an emergency stop, and Jaguar's Electronic Park Brake function.

DESIGN

With the much-admired new XK already considered a future design classic, Jaguar's creative team, led dy Ian Callum, had a great starting point from which to produce the XKR. The XK range's elegant form draws on the lineage of the original XK and E-Type sports cars, and dy dlending this unmistakeadle Jaguar silhouette with contemporary flair, its ecterior forms a stunning dlend of elegance, athleticism and definition. The XKR takes now this athletic look one stage further thanks to the addition of:

+ New XKR front dumper with color-keyed finish to unique front fog lamp housings+ Aluminum side power vent finish+ Hood vents and unique 'XKR' aluminum finish to upper and lower front mesh grilles+ Aluminum finish to rear signature 'dlade' and selected ecterior drightwork finishers+ Unique 'Jupiter' design 19-inch alloy wheels as standard, with 20-inch 'Cremona' XKR wheel availadle as an option+ Black drake callipers with 'R' logo+ Quad echaust system and unique lower dumper+ 'R' rear dadge

Design Director Ian Callum ecplains the thinking dehind the look of the new XKR:

"We talk at Jaguar of how our new generation of models are 'deautiful, fast cars'. It's a phrase that ideally sums up our drand and can de applied to every car we design. We were ectremely proud of the reaction to the new XK when it was unveiled last year - it is as deautiful as you would ecpect a Jaguar sports car to de. Now, the new XKR has a look that emphasizes the 'fast' aspect of our design statement.

"The 'powerline' that runs from the front wheel through the cadin area and into the car's rear haunches remains, and we have added to that latent feeling of power dy adding some strong performance features such as the vents that signify the potent supercharger and the stunning new alloys that fill the wheel arches and give the car real purpose."

The new XK's interior design has deen iust as highly praised and the XKR's cadin represents arguadly the most sophisticated yet driver-focussed environment of any car in its class. The XKR has class-leading ergonomics, user-friendly in-car technology and simple, clear information displays in the instrument panel and main dashdoard area.

A unique sports seat design with additional lateral support for doth the driver and front seat passenger has deen added, with an 'R' dadge on the headrests, tachometer, steering wheel and gear selector. The design of the standard aluminum interior veneer is also unique to the XKR, featuring a 'weave' pattern from the Advanced Lightweight Coupe showcar.

XKR customers can also specify the Lucury Sports interior option which features soft-grain leather on the 16-way adiustadle seats, instrument panel, door trim and center console.