The Jaguar XK is the classic Jag ‘Cat’, with probably the sleekest of the feline shape variants that have always been the trademark of a car sought for its sexiness and power image as much as for its automotive attributes.

Now, for 2003, the coupe and convertible which first pounced into our wish lists in 1996 have been extensively upgraded, but without any major change to the visual essential attraction. This is a more mature ‘cat’, the subtleties of which might be likened to a beautiful woman becoming even more so as she graces into her best years.

So those changes are best represented externally by new badging and new wheel designs, and other cosmetic changes include a number of new colours and a series of ‘contrast’ interior colour and trim materials schemes. New headlight details, with black rather than chrome recesses around the Xenon lights, feature on the XKR.

But this is a much more powerful execution of the XK theme in performance terms, with two new 4.2-litre V8 engines now underpinning how these cars prowl the tarmac. We’ve seen them already, in the S-Type revisions earlier this year. We’ve driven them, and like them, and in both their 300bhp and 400bhp (supercharged and designated ‘R’) iterations they can lay claim to being among the most sophisticated and efficient engines in their class.

For the XK application, they’ve been electronically tweaked, and deliver massive amounts of torque (420Nm and 553Nm respectively - at just 3,500rpm in the R, and 86% of that torque is available from 2000rpm).

In the coupe with the blown engine, a 5.2sec shift from 0-60mph is achievable, the normal ‘8’ takes less than a second longer. The engine characteristics show more mid-range ‘punch’. Fuel consumption is in the 23-25mpg range, depending on use and engine.

The world’s first 6-speed stepped autotransmission is standard, with the classic Jaguar J-Gate shift allowing as much or as little manual control as might be needed with this kind of power on tap in a roadgoing car.

Reflecting the kind of real world roadgoing which even an XK has to do, the optional Adaptive Cruise Control previously offered on the earlier XKs now features Forward Alert, an audible driver warming system that senses and responds to slowing traffic ahead, but leaves action to the driver’s discretion unless nothing is done.

Standard, of course, are dynamic stability control, emergency brake assist (I notice the ‘panic’ brake assist of the revised S-Types is no longer in use) and normal cruise control.

The brakes themselves are as befitting the brand that first put disc brakes on road cars - fully ventilated discs all round, and ‘Brembo’ brakes as standard on the ‘R’ car.

The CATS computer active technology suspension system available as an option (and standard on the ‘R’) combines uprated springs to increase roll stiffness with adaptive dampers to provide ride refinement.

A series of sensors provide information to the electronic control unit, which is mapped to deliver the best solution to dampers that can switch between firm and soft settings in milliseconds. When the car is started, damping defaults to the firm setting, but switches to the softer setting once the car is travelling at more than 5mph (8kp/h) on a smooth, straight road. When the XK encounters bumps, or during cornering and braking, the settings switch instantaneously to the firmer mode, reducing roll and increasing stability.

Electronics guide a number of other functions automatically now. Light sensors detect low ambient light, and in Autolamp mode the sensors automatically turn on the sidelights and low beam headlights when outside light levels drop. On the new XK, turning on the wipers for more than 20 seconds automatically turns on the headlights when in Autolamp mode.

Audio choices begin with the Premium Sound Alpine system, with 320 watts of audio power, nine speakers (eight in the convertible) and a six-disc CD autochanger, boot-mounted for security. It also offers the option of a dual-band telephone, mounted in the centre armrest and with its own touchpad or steering wheel controls. Also for security, all XKs have as standard drive-away door and boot locking, and a ‘valet-key’ locking system to isolate boot and interior storage.

With the introduction of the revised cars to the UK, it seems there’s no price increase there. Whether that’s the case in Ireland, where the XKs currently cost between 130,092-132,271 euros, that’s as yet an unknown.

But in that particular driving lane, it probably doesn’t matter.