We wanted to test the SL600's abilities and, as luck would have it, the perfect opportunity presented itself on Mercedes' international press launch in the South of France. The photographer decided he wanted to catch an early flight back to the UK from Marseille - a decision he took a little over an hour before the plane was due to take off. A further catch was the fact we were 70 miles away at the Paul Ricard circuit.

OK, it's hardly scientific, but as proof of the SL600's outrageous talents it more than serves the purpose. The test pans out like something from one of those PlayStation driving games - get the lensman to the airport on time. But not even in Grand Theft Auto is there a car so suited to a particular task.

Photographers are unable to travel light, so it's fortunate the SL has a decent boot, especially with the roof up. But boot space isn't the issue here - it's what goes on when you fuse throttle to floorpan that's of more interest.

And when you do that in an SL600, things happen. Heading away from the circuit, the N8 winds its way through a series of twisty rollercoaster turns - exactly the sort of stuff you'd imagine a 2025kg roadster to struggle with. Especially since the SL600 wears softer air springs than its twin brother, the more overtly sporting SL55 AMG. Yet at no stage did the V12 feel unduly nose- heavy. That's because Mercedes has filled the engine bay with exotic materials - aluminium alloy abounds, and the cylinder head covers are die-cast magnesium - so that this 493bhp engine weighs only 263kg all-in.

Yet its capabilities were only truly demonstrated when we finally reached the A52. This is perhaps the ultimate pί¿½age car. Press go as the barrier rises, the tyres chirrup and 4.7sec later you'll bid adieu to 62mph (and au revoir to your driving licence if you keep your foot planted). We couldn't resist, and with eyes scanning the horizon, kept the pedal welded; 155mph arrived 21.2sec after launch and the SL600 hadn't even got into fifth. Wow.

It's the manner of this performance that's so special. The engine doesn't dominate proceedings in the way it does with the AMG version. There, the rumbling exhaust telegraphs its intentions in the clearest possible way. Here the key is to provide epic acceleration without making too much of a song and dance about it. So, there's no hissing from the turbos, no more than a distant roar from the dozen cylinders, just an irresistible and unending shove in the back. Exactly what you'd expect from a car that delivers its 590lb ft of thrust in a broad band from 1800-3600rpm. By the way, that's 77lb ft more than the AMG version can muster - for mid-range muscle we reckon the 600 has its bellowing brother licked.

However, for driver appeal, it's the other way round. The SL600 is designed to cover large distances at big speed in relaxed surroundings (perfect for the task we had chosen for it), not thrill on a quick blast like the SL55. The gearbox has a longer final-drive ratio and slightly slower shift times, so feels more laid-back. The softened ABC (Active Body Control) suspension delivers an extremely compliant ride, but, as with the SL500, the steering and chassis reactions feel slightly numb.

In fact, the whole car is slightly subdued. The external mods are deliberately minor - extra chrome on the grille, silver-painted brake callipers, V12 emblems on the flanks and that's it. Inside, bar the well-bolstered seats, there are equally few sporting cues (but an unparalleled amount of standard equipment). In short, the SL600 has a notably more relaxed character than the AMG and will probably attract more mature buyers as a result. They'll have to be equally well-heeled, mind - an estimated price of ΂£92,000 ain't cheap.

And the photographer? Yep, he made the plane.