While you might wonder why Mercedes has both the SL-Class and now the S-Class Cabriolet in its growing line-up, park both cars next to each other and the differences quickly become obvious. Most importantly, the latter is a four-seater, which also requires the fitment of a huge soft-top in place of the SL’s balletic metal folding roof.

Swing open the S 63’s front door and you’ll also be greeted by seats which look more like they’re from a playboy’s yacht than the SL’s slender sports seats. Luxury, power and exclusivity are the order of the day here, with models including the Bentley Continental GTC and Ferrari California T clearly in its sights.

Performance

With more than two tonnes of Affalterbach’s finest to propel, it perhaps isn’t surprising that a 4.6-litre V8 twin-turbo with 449bhp is the smallest engine on offer, badged the S 500. The sweet-spot is arguably the S 63 we sampled, with a 5.5-litre V8 and 577bhp, all aimed towards the rear axle. Incredibly – in the dry at least – depressing the third pedal doesn’t see children gather to marvel at Catherine wheels under its rear haunches, instead you just disappear over the horizon.

You will zap through gears at an alarming rate though, and if you’ve selected manual mode from the seven-speed automatic, you could inadvertently see your head lolling forwards as the engine slams into its limiter, so fierce is the acceleration. It’s partly exacerbated by a relative lack of revs, because peak torque of 900Nm (yes, 900Nm!) arrives at just 2,250rpm, with maximum power following in short order at 5,500 revs. This engine is a heavyweight slugger, and the “whoomphh” emanating from its exhausts is rather reminiscent of a body blow.

Zero to 62mph comes up in 4.2 seconds, while top speed is limited to 155mph, unless you opt for the AMG Driver’s Package, which elevates it to 186mph. For the ultimate connoisseur, there’s also the S 65 AMG, but its 621bhp V12 makes it just 0.1 seconds faster to 62mph. Its huge 6.0-litre engine makes the S 65 heavier and much more expensive, so unless you simply have to have a 12-cylinder – and we’re sure some people do – then the S 63 makes more sense.

Ride and Handling

It doesn’t feel overwhelmed by the power and torque on offer

Perhaps the biggest compliment we can pay the S 63 Cabriolet, is that it doesn’t feel overwhelmed by the power and torque on offer. And, for a car with an enormous gap where the roof should be, that’s no mean feat. There is a small amount of shake through the steering wheel if you hit an awkward bump, but most of the time, the adaptive air suspension simply cossets the driver and emanates stability. Perhaps the weak spot is the steering, which is lacking in feel, but it’s very accurate and its lightness does fit with the relaxed and effortless demeanour of the whole package, which is more akin to an offshore powerboat than a Porsche Boxster. As exciting as a Ferrari California T? Probably not. But, we also doubt it appeals to exactly the same kind of customer as the flamboyant model from Maranello.

Interior and Equipment

The soft-top hood designed specifically for the S-Class Cabriolet is the biggest fitted to any production car.

Where to start? The S-Class Cabriolet is a technical tour de force, with every conceivable gadget to keep you and your passengers comfortable and safe. Impressively, though, the cabin doesn’t overwhelm you with buttons and dials, largely because the huge TFT screens for both the infotainment system and instrument cluster are able to filter the most pertinent information. There are so many sensors and driving aids, you get the impression the S 63 could probably drive itself, if legislation allowed it too. With heated everything and even Mercedes’ Airscarf blowing hot air on the nape of your neck, that might not be such a bad thing on long motorway slogs. With the roof up, refinement is almost as good as the regular S-Class, thanks to the triple-layered hood. Drop it down in around 20 seconds and at speeds of up to 30mph – you have to be stopped in an SL – and it’s also quite cosy in the cabin, thanks to a clever deflector positioned above the windscreen. The rear seats aren’t anywhere near as accommodating as those in the front, but they can be used for short trips or kids, just don’t give them any ice cream or chocolate.

Cost

It’s unlikely you’ll see the S-Class Cabriolet on your company car list anytime soon

This is one of the world’s finest cabriolets, so prices are in the same league as some supercars. The S 500 starts from just under six figures, while the S 63 is around £130k and the S 65 will set you back more like £185k. Oh, and that’s before options. While it’s probably of little concern, economy ranges from 23.5mpg to 32.5mpg, which is actually fairly decent given the prodigious power of each engine. CO2 emissions climb from 204 to 272g/km, so it’s unlikely you’ll see the S-Class Cabriolet on your company car list anytime soon.

Our Verdict

After a drive in the S 63, Beauty and the Beast springs to mind. The S-Class Cabriolet is a wonderfully elegant car, with sumptuous design details, which can also perforate your spleen if you floor the throttle at 2,500rpm. Weighing as much as an SUV, it might not be the last word in delicate handling, but AMG’s big soft-top is actually incredibly satisfying to drive, and it’s simply superb at making you feel good.