IT'S the most expensive Jaguar in the world, it can do almost 200mph, it is -20C so let's go for a drive - with the hood down!

We have just taken the Jaguar XKR-S convertible for a spin - literally - on sheet ice close to the Arctic Circle in Finland.

With studded snow tyres fitted for extra grip, the 542bhp supercar proved it can deliver in some of the most treacherous conditions imaginable.

Drifting sideways around a purpose-built ice track with traction control off, the balance of this high performance version of Jaguar's XK sports car came into its own.

It may have slid out of shape once or twice but get the bite right and this Jaguar is a driver's delight responding precisely to the slightest of touches.

With the stability and traction systems engaged and thanks to the super-grippy tyres, Jaguar's ultimate roadster showed its mettle on roads which would leave many a driver stranded.

The convertible goes on sale on March 1, six months after the XKR-S coupe was launched.

Costing £103,000 it is the most expensive Jaguar since the legendary XJ220 was developed 20 years ago - and that was an incredible £460,000.

Nevertheless, the supercharged five-litre V8 engine in the convertible develops the same amount of power as the super model which went on to become a Le Mans racer in 1993.

Top speed of the XKR-S is restricted to 186mph - that's 300kph - and it has a 0 to 60 acceleration of 4.4 seconds.

Remove the electronic speed limiter and the Jaguar could smash the 200mph barrier.

In every way the XKR-S is a match for anything the likes of Ferrari, Porsche and Mercedes can produce in the supercar league.

Even in the Siberian blast which sent temperatures crashing to critical levels across Europe last week, the open cockpit of the XKR-S was just about bearable thanks to the car's beefy heating system and the lack of turbulence getting under the windscreen.

Roof up - and that's done at the touch of a button in only a few seconds - and the convertible sounds as refined as its metal topped counterpart.

But it is with the hood down where this car excels and the soundtrack from the exhaust is a growling fanfare under acceleration which drowned out the hiss from the tyre studs on snow.

As the fastest open topped car Jaguar has produced the XKR-S is decked out with a rear spoiler, a bulging front bumper flanked with twin air nacelles and a carbon fibre rear diffuser to assist aerodynamics.

The ride height is slightly lower than that of a conventional XK while inside the car is trimmed to the same specification including Jaguar's rotary gear selector for the six speed auto box.

Despite the awesome amount of muscle the XKR-S can deploy it is only slightly thirstier than the regular model averaging 23mpg with emissions at 292g/km.

The R-S models are the flagships of the XK range with a price premium of some £32,000 above the standard cars and are made to order at Jaguar's Castle Bromwich factory in Birmingham.