Jaguar XKR-S
The XKR-S was created with the single aim of building the fastest production Jaguar since the XJ220 supercar of the nineties.

Launched last year originally as a coupe and now available as a convertible, these models are based on the XKR. Power is up to 542bhp, but there's also lowered, revised suspension and new aerodynamic body additions.

We spent a week with both the (£97,000) Coupe and the recently introduced convertible (£103,000), to see if the XKR-S is a match for Audi, BMW and Mercedes performance rivals.

The design might be six years old, but it is still attractive and the additions for the R makeover both toughen it up and bring it right up to date. At the front, there's a unique front bumper with twin nacelles, broad vertical side intakes and a carbon fibre splitter.

At the side, there are chunkier sills, 20-inch Vulcan alloys finished in dark grey, with lowered suspension and darkened air vents.

Whilst at the back, there's a new carbon fibre rear diffuser and that large carbon-trimmed rear spoiler.

Jaguar XKR-S convertible
Inside, considering the hike in prices, the interior for the XKR-S isn't massively different from the XKR, which is a shame. The biggest change is the supportive, high-backed, Recaro-style front sport seats with their contrasting stitching and neat carbon fibre-style fabric.

However, the interior of the first XKR-S I drove, the 12,000-mile French Blue coupe felt quite tired. In fact we don't believe the quality of either of the Jaguars I drove was in line with the price; and definitely not quite up to German standards.

The driving position in both Coupe and Convertible versions of the XKR-S are excellent and the seats are really comfortable. The XKR-S Coupe does have a rear seat, but we reckon even the smallest children wouldn't be happy in the back for long as space is tight.

Still, to live up to its GT intentions there's a practical 330-litre boot, but this drops to 283-litres in convertible form and even more if you put the hood down.

Talking of the hood on the XKR-S Convertible, it folds down in just 16 seconds and roof up we think it is actually quieter than the Coupe.

The Jaguar's supercharged V8 is rated at 542bhp, with torque of 502lb ft; all of this performance equals a 0-60mph time of just 4.4 seconds and a licence-losing top speed of 186mph for both Coupe and Convertible versions.

Jaguar XKR-SConsidering the performance, keeping the CO2 emissions under 300g/km (292g/km) and the Combined fuel consumption of 23mpg is actually quite impressive. Still, buyers of this type of car are unlikely to worry about the running costs.

The 5.0-litre V8 supercharged is proper old-school in the way it delivers its power; squeeze the pedal and there's an almost instant reaction from the supercharger. In fact, it is almost too instant and we'd advise being gentle with the throttle unless you fancy changing ends quickly.

It sounds awesome too, with the rich deep burble resonating through the cabin in the Coupe. The exhaust note deepens in different driving modes, select Dynamic for maximum bass.

Go for the Convertible if you want to hear more of the delicious engine note, as with the hood down you can also hear the exhaust's crackles and bangs on the overrun. It certainly encourages you to drive it harder.

Both our test cars were fitted with the standard paddleshift six-speed auto gearbox. It is well-matched to the engine, but with rivals such as Bentley using eight-speed units, we wonder if more performance and economy gains could be made if such a unit were fitted to the Jaguar?

Show both Jaguars a corner and the XKR-S handles with surprising composure, even without a roof. Yes the ride is hard, but add in responsive steering and high grip levels and we dare anyone not to be impressed by how engaging Jaguar's fastest coupe and convertible are.

Jaguar XKR-S convertibleStandard equipment includes remote central locking, air-conditioning, electric windows, ABS, driver and passenger airbags.

Both models of the XKR-S we tried were fitted with the Bowers&Wilkins soundsystem, which has to be one of the best fitted to any production car. Jaguar's excellent touch-screen sat-nav system is also standard.

So, if you're in the lucky position of being in the market for a new sportscar, should you go for an XKR-S and which is best Coupe or Convertible? For us, the interior isn't special enough or well-built enough to justify the price.

In fact, the Convertible's slightly softer settings make the drop-top our pick of the two. There's the same performance punch, but the ride is suppler making it the better all-round tourer.