Both the Mercedes S63 AMG coupé and Bentley Continental GT Speed have a commanding presence on the road
Together these cars pack a total of 1203bhp
GT Speed owners will be visiting the pumps more often - it averages just 19.5mpg
The S63 is claimed to be capable of averaging up to 28.0mpg
The Bentley's dashboard reflects its older lineage
The Mercedes' interior feels very contemporary, not only in its design but also in its provision of tech
The S63 AMG coupé costs £125,595
Both cars can reach 62mph in the same time - 4.2 seconds
The Continental GT Speed is the more expensive option here, at £156,700
The GT Speed has the higher top speed, at 206mph compared to the Merc's 186mph
The Mercedes has clever suspension, but the Bentley manages to keep up
Both cars weigh north of 2000kg, but the Bentley is the heavier car, at 2320kg
Both cars feature automatic transmissions, but the Bentley gets an 8-speed compared to the Merc's 7-speed
In part thanks to its 80-litre fuel tank, the Mercedes will travel further than the Bentley. It has a range of 420 miles
Both cars feature multi-link suspension setups at the rear
The Bentley builds driver confidence quickly, aided by its good steering
The Mercedes is 221mm longer than the Bentley, measuring 5027mm
The third car absent from this test is Aston Martin's Rapide S
The Bentley is more compact, or less big, than the Mercedes
The Mercedes bests the Bentley on storage space, offering 400 litres in its boot
The S63 AMG coupé represents a clear threat to the likes of the Ferrari FF
The GT Speed is Crewe's fastest-ever production car
Our Bentley Continental GT Speed test car arrived on 21-inch alloy wheels
Powering the Bentley is a 6.0-litre W12 engine with 626bhp
Under the bonnet of the Mercedes is a 5.5-litre twin-turbo V8 engine developing 577bhp
The quality and choice of materials on offer in the Bentley inject real class
Carbon fibre enhances the look of the GT Speed's cabin
Most infotainment functions are operated from this touchpad controller
Both cars have their charms, but it's the Mercedes that wins here
Although there is no formal definition, the UK government recognises a mountain to be any peak greater than 2000ft, of which well over 100 exist within the UK.
And given the vastness of the great Brecon Beacons and Snowdonia national parks, you might expect Wales to be home to a fair chunk of them. But it’s not. It has just eight.
The two most famous are the 2907ft Pen y Fan, which lies south-west of Brecon, and the 3560ft Snowdon, the highest in respectively the south and north of the country.
Handily for a hack looking for a hook to a story about two huge, powerful cars, the route between these two huge, powerful peaks takes in some of the best driving roads in this or any other country in our still intact United Kingdom.
The Bentley Continental GT you will know, for it has been a fairly frequent presence on these pages since its launch in 2003, and despite being regularly and at least once comprehensively updated on the way, it remains essentially the same car.
The 6.0-litre twin-turbo W12 motor powering this Speed version isn’t that much changed, either. Yes, its power output has been tickled up by another 10bhp to 626bhp, but given that this engine developed 552bhp in basic form upon introduction over a decade ago, that’s not such a leap.
Then again, and for these purposes at least, there’s some benefit to its consistency, for its role here is the provide the benchmark for the other car now pulling into the car park opposite the Storey Arms on the A470, the start point for most hikers on their way up Pen y Fan.
That car is, of course, the Mercedes-Benz S-class coupé, perhaps better known as the replacement for the CL. In S63 AMG guise as tested here, its 5.5-litre twin-turbo V8 has a trifling 577bhp but, lacking the Bentley’s four-wheel drive hardware, it weighs a quarter of a tonne less despite being both longer and taller.
The upshot is a fractional power-to-weight advantage to Mercedes that would matter little were it not backed by a monstrous torque-to-weight advantage, too. The Speed is Bentley’s fastest road car yet and it looks likely to be blown to dust by a Mercedes based on a pre-existing saloon with a smaller engine and fewer cylinders.
The price differential between them makes painful reading, too, for Bentley fans. At £156,700, the Speed costs over £30,000 more than its rival, money that the Merc buyer could spend speccing his car to the nines or just buying a brand-new Lotus Elise for a bit of fun on the side.
And I can think of no other two-door car, save a Rolls-Royce Wraith, capable of making the Bentley look so small. But it does: the Mercedes coupé might sit on a shorter wheelbase than an S-class saloon but it still logs in at well over five metres in length, longer even than four-door rivals such as the Porsche Panamera and Aston Martin Rapide S. Its lines flow beautifully, but next to it, the Bentley looks taut, compact and purposeful.
Technologically, it is to the Bentley as a super-computer is to an abacus. Were the roads not so winding, a passenger could have happily whiled away the entire journey from south to north trying to figure out the full range of its functionality and still found work to do at journey’s end.
This is a car that uses cameras as eyes to control the suspension, the cruise control and even the steering – on the motorway, it really will drive itself. Tick the right boxes on the options sheet and you can have a seat with a longer list of massages than a five-star Bangkok hotel and a Burmester music system with more controls than an Abbey Road mixing desk.
But we’re not here to fiddle with gadgets, however enticing they may be. We’re here to drive and I make no excuses for falling on the S-class keys first.
The route up past Builth Wells, Llandridnod Wells, Rhayader and towards Betws-y-Coed and Snowdownia is one of the best drives anywhere on the mainland, especially if you keep off the A470 and stick to the often more direct and always less travelled B-roads.
It was always going to be a challenge for such cars. Despite their sleek lines, these are not pure-bred sports cars nor even purpose-built GTs. Both are spun off saloon car architectures (let’s not forget the Bentley’s Volkswagen Phaeton ancestry) and even the lighter Mercedes weighs the wrong side of two tonnes.
But at times, 663lb ft of torque can make even such evident avoirdupois seem irrelevant. Mercedes’ home-grown seven-speed transmission is annoying because it is neither as smooth nor as intuitive as the ZF eight-speeder in the Bentley, but once you’ve learned to lock it in a ratio and let the torque do the work, this is a mightily fast car, and by any conventional standard you like.
The four-wheel-drive versions available in left-hand-drive markets will pop sub-4sec 0-62mph runs all day long. And that engine! I am by both instinct and disposition suspicious of downsized turbocharged engines but this one is magnificent.
Its performance is not characterised by the turbos at all, merely helped along. They blow relatively little boost, allow for a double-digit compression ratio and, as such, offer neither lag nor impedance to the engine’s voice.
Throttle response is electrifying, the noise the very blood and thunder you’d dream of in such a car, and the thrust… well, it is simply majestic.
Sad to say, the Bentley engine struggles by comparison. The issue is not its relative lack of torque or that its extra power is entirely stymied by its additional weight, because this is still a massively fast car. But it can’t do the subjective stuff anything like so well. Its voice is dull and its throttle response slack by comparison.There is no joy in this engine and, to be honest, it has been that way since it was born.
We’re deep into mid-Wales and I’m fiddling with the S63’s chassis set-up, trying to decide if its Pendolino-like ability to lean into corners is an asset or gimmick.
I decide that on give-and-take roads such as these, where it sometimes struggles to distinguish between curves and cambers, that it’s best left alone and settle for Sport mode instead.
I can remember being blown away by how well the S63 AMG saloon handled, but that was by the hardly high standards that you’d expect from a luxury limousine. The bar is far higher here and the coupé is clearing it, but by less than I’d thought.
There’s an artificiality to the steering that makes the car difficult to place on the road, and despite the arsenal of electronic suspension trickery at its disposal, it lacks the iron-fisted body control that I’d expected.
Then again, these are tough roads and if the Merc is finding them hard, how is the Bentley faring? Oddly, every time I look in the mirror, it is still there and showing no apparent signs of struggling to keep up.
The reason why soon becomes clear. In every dynamic area save perhaps braking, it is objectively inferior to the Mercedes. Subjectively, however, it is a rather different matter.
Out here where there is no such thing as a constant radius bend, where the only thing that changes more often than the weather is the camber and surface of the road, it’s not torque or power that’s the chief determinant of your point-to-point pace: it’s confidence.
And this the Bentley supplies. Its old-style hydraulic steering has a feel that you’ll not find in the Mercedes and, despite their passivity and relative technological backwardness, its dampers retain better control of the Bentley’s body.
There’s less pitch and heave, and in the medium-speed turns that characterise this part of the world, I’d call it the more nimble of the two, were ‘nimble’ a word you could ever use to describe a 2.3-tonne four-wheel-drive Bentley with a 6.0-litre 12-cylinder twin-turbo motor. Then again, it is shorter in the wheelbase than the Benz, and substantially so, so perhaps we should not be so surprised.
How concerned should we be about such issues? These are cars more sporting than sports and there are many who’d argue that there are considerations that should take their place ahead of mid-corner adjustability in the priority queue for such devices.
Which is fair enough, but when I turn my attention to less exciting but perhaps more relevant considerations, I find them harder to separate.
I should prefer the Mercedes because, again, if you think about it at all sensibly, it’s just the better car. Its ride is more deft and its interior more spacious in front, back and boot. It’s undoubtedly quieter at a constant cruise and there’s so much to play with in here that years from now you’d likely still be finding new functions that you’d hitherto never known existed.
Nor can you quibble with the cabin design, where Mercedes has been able to tempt traditional materials into entirely harmonious living arrangements with a post-modern dash of thrilling complexity and sophistication.
The Bentley has little to offer in reply and its dashboard, with its simple analogue dials and a navigation screen not unlike that in a Volkswagen Golf, seems antediluvian by comparison.
And yet there’s a sense of occasion in here, a feeling of well being amid those exquisitely judged and matched hides and veneers that speak of another set of priorities, an innate class that not even the Mercedes can match. For the less gadget obsessed, it is a wonderful place in which to pass time time.
Despite an entire day on the road, by the time we reach the foothills of Snowdon, a clear victor has still to emerge. Despite all the common ground they share, these are profoundly different cars.
Bentley has excelled itself in imbuing the Speed with a timeless quality that the Mercedes cannot match, but if it is performance, ride, refinement or space that matters most to you, the Merc is just better, as well as £30,000 cheaper.
Even in this relatively price insensitive part of the market, that counts. In hackneyed terms, the head directs you straight to the Benz, while the heart implores you to go for the Bentley. I decide to sleep on it.
Soon after dawn the following day, we finish shooting and I’ve rarely seen this part of the world look more beautiful. But I am tired, there are many long hours of driving ahead and time is short. Bentley or Mercedes?
At last, the decision is clear. I walk straight to the Bentley, take one last, wistful look at that gorgeous interior and then, and only slightly guiltily, settle into the Mercedes and head for home.
Bentley Continental GT Speed
Price £156,700; 0-62mph 4.2sec; Top speed 206mph; Economy 19.5mpg; CO2 338g/km; Kerb weight 2320kg; Engine W12, 5998cc, twin-turbo, petrol; Power 626bhp at 6000rpm; Torque 604lb ft at 1700rpm; Gearbox 8-speed automatic
Mercedes-Benz S63 AMG coupé
Price £125,595; 0-62mph 4.2sec; Top speed 186mph (with Driver's Pack); Economy 28.0mpg; CO2 237g/km; Kerb weight 2070kg; Engine V8, 5461cc, twin-turbo, petrol; Power 577bhp at 5500rpm; Torque 663lb ft at 2250rpm; Gearbox 7-speed automatic
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