Given that the old 4.2-litre model wasn't exactly deficient, it's good to see a raft of small but significant changes have managed to keep the XK at the top of the GT tree

Generally car makers aren't considered newsworthy enough to make primetime viewing ­ but recently Jaguar has been gracing our screens almost as much as BBC economics doom-monger Robert Peston. The reason? The Indian-owned firm is looking for financial reassurance from the UK Government during these tough times.

It seems an oddly downbeat backdrop against which to launch a brace of new high-performance engines but Jag is coming out punching, convinced its revised XF and XK boast the armoury to spearhead a product-led recovery. Yet appearances can be deceptive. Just as Jaguar is in far better health than the media would have you believe, with sales up on 2008, its new 380bhp AJ-V8 Gen III V8 petrol and 272bhp 3-litre twin-turbodiesel (XF only... for now) are cleaner, greener and considerably more potent than their already impressive predecessors.

There's a number of subtle cosmetic improvements on the XK. A re-profiled bumper, designed to evoke E-type memories, adds character, while the cabin has received a brush-up. This not only lifts its quality and visual appeal but also sees the addition of the XF's oddly effective cylindrical 'JaguarDrive Control' for the updated ZF six-speed auto.

However, it's on the road where the changes are instantly felt. The new engine has been tuned to produce around 30% more torque at any revs ­ and that translates into better throttle response and additional urge. In terms of straight-line speed, the 2010 XK is close to the old supercharged R, and a genuinely quick proposition.

The direct-injection motor's soundtrack is as evocative as before, rumbling contentedly when loping but bellowing like a true racer when floored. Yet, welcome as the extra performance is, we can't help feeling the improvements to the suspension set-up are even more impressive.

The Adaptive Dynamics package may sound like marketing guff, but the computer-controlled damping is actually very effective. Attack your favourite twisting road in Sport mode and the quick steering and low-roll cornering combine beautifully to allow the driver to simply flow.

In true Jaguar style the XK covers ground in such an unruffled manner our only real criticism is that pushing it on a challenging road seems all too easy. And it is a great driver's car, which leaves the stiff-legged opposition from BMW and Mercedes-Benz some way behind.

Given that the old 4.2-litre model wasn't exactly deficient, it's good to see a raft of small but significant changes have managed to keep the XK at the top of the GT tree ­ as well as posing some awkward questions for Aston Martin.

Buy with confidence, and enjoy...