Mercedes-Benz CLS350 vs Mercedes-AMG S63

What's the difference?

The Mercedes-Benz CLS has proven to be a niche hero, creating a segment and then evolving into something even more elegant, while keeping its unique appeal. A beautiful, modern cabin and the new engine in the CLS 450 provides the swiftness to match those looks.

Both of these vast vehicles are phenomenally comfortable - this is the kind of car that Mercedes does so well, and has done for decades. The S Class is rarely a disappointment but it's difficult to believe that such a big, heavy GT car can also dance the way the S63 does.

The S560 is far more weighted to being a GT - supremely comfortable with that active suspension, a growly, refined V8 and a cabin full of gadgets and comfort. The S63 is altogether more aggressive, to look at and to drive. Lopping the roof off both of them adds weight but, like any cruiser, also puts you out in the sun, the breeze and into your surroundings. Plus, in the case of the S63, you get more exhaust noise.

They're two very different cars and not just because of the engine. After all these years admiring it from afar, the S63 has delivered on my teenage expectations - fast, smooth and utterly mad.

The new-generation CLS has arrived looking slipperier than a cake of soap on the bottom of the bath. This model has always had svelte styling, but things have become even smoother with Benz’s design chief Gorden Wagener insisting more lines be removed in the creation of this latest version.

So, while there’s the familiar profile of that roof tapering down into the boot lid, the long rear overhang and that sliver of a window opening arching and turning down sharply at the rear, it's a more flowing design now that there are less edges to break it all up.

A new ‘shark nose’ grille opening, and broad bonnet adds a hunk of muscle car toughness to the CLS’s face. But it’s refined thuggery, with that single-louvered ‘diamond studded’ grille flanked by flush-mounted headlights. The tail-lights, too, are so contoured to the body around them they look painted on.

As CarsGuide senior editor Matt Campbell pointed out in his review of the CLS at the international launch, the car looks far better in the metal than it does in any photo.

The CLS is based on the E-Class, sharing its platform and technology, but it’s about 20mm longer (at 4988mm) end-to-end. That’s almost 50mm longer than the previous generation CLS, too. At just over 1.4m tall the CLS is low-slung but wide at 1.9m across (almost 2.1m including mirrors).

The CLS’s cabin mirrors that of the E-Class, too, with a sweeping dashboard which flows through into the doors, two large landscape displays for your instruments and media, an oversupply of air vents and some darn sexy lighting. It’s a luxurious, stylish, comfortable, but snug setting cocooned by padded leather and polished surfaces.

The Australian CLS has been fitted standard with the AMG interior and exterior packages.

You can pick from 11 colours – eight of which are no-cost options and include, 'Polar White', 'Obsidian Black', 'Iridium Silver', 'Citrine Brown', 'Graphite Grey' and 'Cavansite Blue'. Optional colours include 'Hyacinth Red' and 'Selenite Grey Magno'.

The S Class Coupe is obviously related to the sedan but manages a svelte appearance. Slimmer hipped and with a more Coke-bottle shape, the Coupe - if you squint a bit - has a bit of the classic old pagoda about it. Obviously you can't do pillars that slim anymore, but the glass roof takes away some of the visual weight inside and out. 

The cabriolet's roof is nicely integrated and looks good when it's  up, which isn't always the case.

They all look long, though. It's obvious to see why the cars all run on 20-inch wheels - anything smaller would look hilarious.

The cabin is a fairly sensible re-imagining of the E-Class. The big twin-screen layout of the dash and multimedia system seems a bit more at home here. The chintzy Burmester speakers in the doors let down an otherwise classy cabin, which steers clear of otiose vulgarity in looks and materials.

Remember how I said you were going to have to surrender something if you wanted a CLS? Well, yes, you’ve have to surrender your hard-earned money, but you’ll also have to give up quite a bit of practicality.

That swooping roofline makes entry into the front seats a bit precarious for people of my height (191cm) trying to swing themselves into the cockpit without clocking their heads on the A-pillar.

The impracticality only gets worse with entry into the back seats, and legroom in there for me is tight, too.

I can only just sit behind my driving position thanks to the contoured seat backs. Headroom is also limited.

It’s worth pointing out that this time the CLS is a five-seater – the previous generation sat just four.

Storage isn’t bad, running to a deep centre console bin with a split lid, there are two cupholders up front and another two in the rear fold-down armrest along with another covered drawer, and all doors have small bottle holders.

The CLS’s boot capacity is 520 litres, and the rear seats fold 40/20/40 to provide extra space.

Well look, if you end up in the back of the S Coupe, it's not a riot of space. Obviously it has back seats (the SL doesn't even squeeze a jump seat into its considerable length) but they're for occasional, if luxurious, use.

The boot is a reasonably decent 400 litres, obviously the cabriolet loses a few litres with the roof folded. Front and rear passengers will both enjoy a pair of cupholders and the whopping long doors will each hold a bottle.

One thing hasn't changed in nearly 20 years - the S isn't cheap. Available in coupe and cabriolet, the S560 starts at $314,900 for the former and $336,900 for the latter. Step up to the S63 pair and you'll pay from $370,500 for the coupe and $399,900 for the cab. If you're super keen for something spectacular, the twin-turbo V12-powered S65 is available for between $508,900 and $520,500, and features Swarovski crystals in the headlights, for some reason.

As you can imagine, there's quite a bit to cover, so for both cars I'll stick to the edited highlights. The S560s roll on 20-inch alloys, has a 590-watt 13 speaker sound system, digital TV, auto parking, active cruise control, panoramic glass roof, Nappa leather, active seats and power-closing doors.

It also comes standard with a heating pack that not only heats the seats but the steering wheel and centre console. In the cabriolet you also get the 'Airscarf' neck heater.

Both cars also feature's Mercedes' Magic Body Control with curve function. More of that wacky feature later.

The S63 AMG is a step up in power, price and spec. One notable change from the S560 is the loss of 'Magic Body Control', which is replaced with mere air suspension. The 20-inch alloys are 10-spoke forged units, the brakes higher performance composites with red calipers, while an AMG sports exhaust brings the noise.

Naturally, both are swathed in high-quality leather and feature dual-zone climate control, heated and cooled electric seats that adjust in every direction, deep carpets, keyless entry and start, fully digital dashboards and just about every gadget to which you can point your imagination.

Entertainment and sat nav are via Mercedes' 'Comand' system, which is displayed on a massive 12.3-inch slab of glass at the top of the dashboard. The 13-speaker Burmester-branded system is predictably impressive and with Apple CarPlay and Android Auto, you only have to use the basic software for the radio or various car controls.

If you’ve skipped straight to this bit you’ll have missed news that there’s no longer a diesel engine in the CLS line-up. Instead you have a choice of three petrol engines – one for each grade and all of them are new to the model.

The CLS 350 has a 2.0-litre four-cylinder turbo-petrol engine producing 220kW/400Nm. That grunt is delivered to the rear wheels via a nine-speed automatic.

The CLS 450 4Matic has a 270kW/500Nm 3.0-litre in-line six-cylinder engine with a twin-scroll turbo and like the Mercedes-AMG 53 above it has an integrated electric motor called an EQ Boost. While it’s a hybrid system of sorts the electric motor doesn’t drive the wheels, instead it recuperates kinetic energy and charges the battery.

The CLS 450 uses the nine-speed auto, as well, and is all-wheel drive.

The Mercedes-AMG CLS 53 4Matic has the same transmission and engine as the CLS450 but has been given a heftier twin-scroll turbo charging system and tuned to produce even more grunt at 320kW/520Nm. The 'EQ Boost' performs the same function as in the CLS 450, but also provides power to an electric turbocharger. The Mercedes-AMG CLS 53 4Matic is also all-wheel drive and uses a nine-speed automatic.

All four coupes and cabriolets ship with Daimler's formidable 4.0-litre twin-turbo V8. The S560 scores 345kW/700Nm to drive the rear wheels through Benz's own nine-speed automatic. With all of that available, the S560 will crack the ton in 4.6 seconds and make a wonderful racket on the way.

Moving on to the S63, the same engine delivers a massive 450kW/900Nm. The run from 0-100km/h is dispatched in just 3.5 seconds and if I thought the S560 made a good noise, the S63 with its standard sports exhaust makes a better one. Again, Mercedes' nine-speeder is along for the ride.

This is a good place to remind you (again) that only one CLS grade was available to drive at the Australian launch – the CLS 450, and we were only given the claimed fuel economy figures for that model.

After 197km through, on a route that bumper to bumpered its way out of Melbourne CBD and headed the long way to the airport via Woodend. our car’s trip computer was reporting close to an average of 10.0L/100km.

The lower-powered 560 drinks 98RON at the rate of 8.5L/100km for the coupe and 9.9L/100km for the heavier cabriolet.

The S63 ups the ante with 9.9L/100km for the coupe and an identical 9.9L/100km for the cab.

Our launch program contained some...er...spirited driving, which would explain the mid to high-teens fuel figures.

A reminder again, folks – Mercedes-Benz only had the CLS 450 available to drive. Okay? On with the review…

Nobody likes a traffic jam, apart from maybe taxi drivers. But sitting in a CLS deep in Melbourne’s CBD, stuck in road-work-infested roads, choked with cars going nowhere was as pleasant as the experience could be. 

Plush seats, pretty lighting, air filtered and fragranced, air suspension cushioning the patchy tarmac underneath as we wriggled our way north towards Mount Macedon and country roads.

If you read another review calling out a large degree of wind noise filtering into the cabin, they’re right and wrong. See, the weather was apocalyptic as we hit the motorway. Trees doubled over kind of windy, and sure you could hear it rushing past the windows when we were at 110km/h, but you could also hear it clearly when we were at 30km/h.

I like gadgets and so it was about 15 seconds into the motorway stint that I tested out the active cruise control, and automatic lane changing, which works near perfectly.

As the roads became more winding, I switched drive modes to 'Sport', firming up the suspension and steering, at the same time prompting the transmission to kick back into a lower gear.

This is a stable-feeling car, well balanced and effortless to steer. Smoothness is a word for everything it does, including covering the ground quickly.

While that acceleration is rapid, it’s not quite exhilarating, and the engine note under load is a little high pitched for a thug like this.

CLSs of the past were known for being a bit more aggressive and feistier, but this one seems to have mellowed in its third generation. I don’t see any issues with this. There are other angrier Benzs if that’s your thing.

Let's start with the S560. That smooth V8 rumble is all you'll ever hear if you just slot into drive and go for a leisurely spin. The nine-speed automatic continues to be a revelation to me - in the GLC63 it's good and here, once again, it's excellent, finding the right gear for the occasion and riding the fat torque curve. Other nine-speed autos are not very good at all.

The test route for the S560 played to the strengths of the car. It had some lovely winding roads, which brought the trick suspension into focus - the Magic Body Control with curve function is hilarious. While the active suspension works hard at all times to ensure the ride is smooth and drama free, the Curve mode (no, really) actually leans the car into corners.

Those of you who remember the video game Wipeout 2097 will be big fans of Curve mode. As you approach a corner, you turn the wheel and then the car leans into the bend. This isn't active damping reading the road, it's the outside suspension lifting the car and the inside lowering it, so the car feels like it's gliding, like a hovercar. It's wild but oddly calming. Mercedes reckons it's great for those who get car sick. As I didn't have my wife on hand to test this theory - she chucks at the first sign of a corner - I couldn't verify this claim. That will have to wait.

The S63 AMG is a completely different proposition. The air suspension is more than up to the job of helping smother the effects of the car's considerable weight, meaning that no matter what you're up to, the car feels reasonably light on its feet. It never feels small, though, commanding the respect of the driver and plenty of space from other road users.

And boy, do you need some space if you kick the S63 into Sport mode. In true AMG style, the electronic reins relax and the big luxury coupe cheerfully kicks off. The tail will wriggle under an unsympathetic right foot, that signature V8 roar, crackle and hiss filling your ears. The S63 is always the harder-feeling car, but it delivers with a more sporting drive than the S560.

Being the generous soul I am, I volunteered to return the S63 to its home for the evening rather than consign it to the back of a truck. On the back roads I took to reach the highway, it was rock solid - fast, predictable and a lot of fun. Once I found the boring straight bits, it turned into a supremely comfortable cruiser, ticking along in ninth at the legal limit (and being Melbourne, it was very much the legal limit), dispatching overtaking with barely a flex of a toe. 

The active cruise took the stress of keeping away from the State Revenue Office's clutches while being quiet and utterly pleasant.

The S-Class coupe comes loaded with eight airbags, ABS, stability and traction controls, forward and reverse AEB with pedestrian detection, reversing camera, crosswind assist (I know, right?), traffic-sign recognition and reverse cross traffic alert.

The S-Class Coupe does not have an ANCAP or EuroNCAP rating.

The CLS is covered by Mercedes-Benz’s three-year/unlimited kilometre warranty. Servicing is recommended every 12months/25,000km for the CLS 350 and CLS 450, while the CLS 53, like all AMGs needs to visit at 12month/20,000km intervals.

Mercedes-Benz says a capped price servicing plan will be available, but has yet to release the prices. We’ll update this as soon as the costs have been announced.

Mercedes offers a three-year/unlimited-kilometre warranty with roadside assist for the duration.

The company also offers both service plans (where you pay up-front as part of the vehicle purchase) and capped-price servicing on the coupes. Servicing over three years is in the order $2500.