Review: 577bhp Mercedes-AMG S63 Cabriolet

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Welcome to the ultimate incarnation of the Mercedes S-Class Cabrio: the 577bhp, bi-turbo V8-powered S63 AMG.

Well, the ultimate S-Class Cab for now at least. There’ll soon be an S65 AMG offering a surfeit of V12 fury, but this £135,675 S63 soft-top is all a sane person could ever really need. It’s £8000 more expensive than the coupe - a bit of a favourite here at TG - but due to packaging the triple-layer electric roof, you can’t have the clever suspension that reads the road ahead for bumps and leans into corners.

And despite that, I’m guessing the S63’s quite a bit quicker than a ‘normal’ S-Class Cabrio?

Prodigiously. Over the £25,555 cheaper S500, this S63 weighs in with an extra 700cc of capacity, 128bhp and 148lb ft of torque. The result is 0-62mph in just 3.9 seconds, and a suitably quicker arrival at the limited 155mph top speed. Not to mention your destination. And they’re going to do a V12. For £192k. Our minds are duly boggled.

Not to labour the point, but this is a 2110kg, five-metre long machine. It has massaging seats, heated armrests, heated headrests, and computing intelligence to leave Skynet looking dense. Yet it’ll do 0-62mph in 3.9 seconds. We’re used to monster performance numbers these days, but come on: a soft-top S-Class that’ll out-accelerate a Porsche 997 Turbo has to be worth a slap on the back for AMG’s engineers.

One caveat, though – the car we’re testing is left-hand drive, and as a result has AMG’s 4Matic all-wheel drive system. That allows for sub-four second sprints to national speed limit velocity.

If you live in the UK and order the car in right-hand drive, it’ll only be available with rear-wheel drive. So, Brits put up with a few tenths off those acceleration stats and several thousands pounds-worth of extra tyre bills.

How does it sound?

Fairly naughty for what’s supposed to be the most dignified and opulent of all the Mercedes cabrios. AMG has made the best fist of the recent rush to downsize engines with smaller turbo units – its V8s have kept not just the barrel-chested torque and creamy response, but also their personality-laden, rolling thunder soundtrack.

The S63 is powered by the 5.5-litre V8, instead of the ‘hot-vee’ 4.0-litre you’ll find in the C63 and AMG GT, but its less aggressive, more melodious tones suit this car.

In fact, when you remember the gargantuan thrust under your right foot, the S63’s not quite as audible as you might imagine, roof up or al fresco. It’d be nice if, once Sport mode is selected, the engine bellowed just a little harder. The less powerful S500 is actually more rumbly and cockle-warming when you’re just mooching around. This car is a born moocher, after all.

What’s it like to drive?

You tend not to drive the car to the redline and use every last horsepower. Lean on the torque instead. The car develops 663lb ft – one solitary foot-pound less than a McLaren P1. That’s channeled through AMG’s tough old seven-speed gearbox, rather than the nine-speeder lesser models slot in.

Whatever you do with the gearbox – Sport mode, Comfort mode, paddles, no paddles - it feels behind the rest of the package. It’s flustered on quick downshifts, hesitating until the computer is good and ready before slotting the gear.

This is a cabrio, does a finicky transmission matter?

Not as much as in the more sorted Coupe. This is a noticeably less sporting piece of kit. Obviously a fair proportion of the people who buy an S-Class Cabrio will default to the AMG because it’s the most expensive, not necessarily because it’s quickest or best at overtaking.

But this S63 AMG isn’t the S-Class Cabrio at its absolute best. The sheer speed it accrues with such hilarious, unthinking disdain only highlights the hesitant gearbox, and the remote steering. It’s almost as if the car would rather be driving itself than trusting your grubby mitts with it, and given this is as autonomous as Benzes get right now, that’s hardly surprising.

The car’s not a cinch to place on the road as a result, and not as relaxing as a big land-yacht ought to be. The slower S500 has a nine-speed gearbox, and actually shifts with greater obedience as it’s juggling less torque. Irony of ironies, the non-AMG car is actually more responsive.

And at some point, you are going to have to get the thing stopped, or around a corner, and though the S63 has all the necessary hardware, you notice the weight of the thing, big-time. All of this intimidation results in one uncomfortable truth: you don’t end up driving the 577bhp S63 Cabrio that fast. Or if you do, it’s a brief, naughty thrill, unless you’ve got the sort of space that lets Veyrons reach their upper echelons. Be in no doubt, an S63 Cab is a magnificent means of transport – a truly feel-good motoring experience. But this isn’t a performance car first, cabrio second. It’s more a big luxo-cabrio that happens to do almost 200mph if you’re feeling silly.

All of which is jolly exciting, but the non-AMG S500 is possibly sweeter still. Less power, a less frantic race to get it slowed down, and a truly blissful motoring experience as a result. Question is, will anyone ready to drop over a hundred grand on a V8 Benz drop-top notice it on their way to the AMG end of the brochure?