Can the Mercedes-AMG CLS 63 S provide sensationally entertaining, as well as civilised, executive transport?

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Although we’re generally remarkably impressed with the inherent efficiency of modern forced-induction motor, why is it that we welcome the 5.5-litre, twin-turbocharged motor in the CLS 63 S with a mild sense of trepidation? 

Mainly because we’ve been so won over by the depth of character and performance of the naturally aspirated 6.2-litre V8 it replaces. However, this engine not only has more grunt than the 6.2-litre V8 but is also 32 percent more efficient.

We already know the CLS coupé to be excellent luxury transport

And in no installation does it make more sense than in the Mercedes-Benz CLS. We already know the four-dour coupé to be excellent luxury transport or for those craving extra practicality a shooting brake, and as a sort of high-end enthusiast’s limo it can justify having 576bhp better than most other Mercedes

But there’s no point to having such extravagant outputs – or an equally extravagent price – if it’s not sensationally entertaining, as well as civilised executive transport. And that’s not an easily achieved compromise.

In 2014, the Mercedes-Benz CLS was given a facelift, which largely was condensed to a new front grille, bumper and headlights, while the inside was given a light sprucing up. The CLS 63 S gained a wet clutch version of its seven-speed automatic as AMG seeked faster shifting to help unlock its performance potential.

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Mercedes-AMG CLS 63 S rear

Mercedes-AMG claims the CLS 63's looks are inspired by the SLS supercar. Clearly, there are similar styling cues here and there – particularly at the front end – but we suspect that when you see the CLS 63 , you will notice that it looks predictably like a standard Mercedes-Benz CLS after some heavy hormone treatment.

But still, the results are far from unappealing. Our test car came with the optional AMG carbon trim package, which includes carbonfibre door mirrors and rear diffuser, but we’d say that it’s unnecessary chintz on an otherwise appropriately muscular yet understated design. 

Mercedes claims the CLS 63's looks are inspired by the SLS supercar

Far more important than any dress change is the substance it conceals. And that starts with the all-aluminium, twin-turbocharged 5.5-litre V8, which puts out 576bhp from 5500rpm and 590lb ft from 1750rpm to 5000rpm.

That’s an increase of 27bhp, over the pre-facelifted CLS 63. The rewards of the new motor don’t stop at a power hike, but also extend to emissions and consumption, which, at 230g/km and 28.5mpg, are a huge step forward from the 6.2-litre V8’s.

Much of the environmental improvements are down to the new, standard-fit seven-speed automatic transmission, which loses the torque converter of old and gains a wet clutch. This new ’box – available in AMG models only – also brings with it standard stop-start. 

Riding on wider tracks, with multi-link suspension at both ends and self-levelling air suspension on the back axle only (coil springs up front), the CLS’s active damping adjusts automatically to suit the road and driving style, depending on which of the three suspension settings the driver has selected.


Mercedes-AMG CLS 63 S interior

Given that Mercedes-AMG also has the E-Class E 63 set to join the range, it could be forgiven if the CLS was, comparatively, considerably less capacious. Thing is: it isn’t. 

Although the E-Class has a superior boot volume and rear seats that could allow it some executive private-hire work, the Mercedes-Benz CLS can easily hold four normal-sized adults in its interior. A boot volume of 520 litres is unlikely to be a deal-breaker, either, especially given that the rear seats split and fold, although 520-litres available on the Shooting Brake would no doubt quash that issue.

The CLS can easily hold four normal-sized adults

The interior layout is as similar as you’d expect to the standard CLS’s, but the details that typically tell a performance car from its cooking siblings are all there. The optional carbonfibre trim serves no discernible weight-saving purpose but looks the part. The dials are black rather than part-white faced and there’s suede on the steering wheel rim, which we found to be too square for our liking.

Most significant, though, are some exceptionally adjustable and supportive front seats (in which all of our testers found a top-notch driving position) and the migration of the gear selector from behind the steering wheel to its rightful place on the centre console. The selector is neatly designed and topped with AMG’s logo. Next to it, and appropriately angled towards the driver, are buttons that alter the damper, gearbox and stability control settings. 

All of this could feel a little contrived, but somehow it doesn’t. Not quite. Instead, as driving environments go, it takes some beating.

As for the CLS 63's standard equipment, expect to find 19in alloy wheels, an aggressively-styled bodykit, a sports exhaust system, LED headlights, a reversing camera and an electric sunroof on the outside, while inside there is keyless entry and start, electrically adjustable and heated front multi-contour seats, climate control and a Harman and Kardon sound system.

The CLS 63 S also comes with Mercede's fully-loaded infotainment system complete with an 8.0in high-resolution display, Bluetooth, DAB radio, USB connectivity, sat nav and smartphone integration.


Mercedes-AMG CLS 63 S side profile

It is best not to look too closely at the headline performance figures we recorded for the CLS 63. We picked our moment to visit the test track as carefully as possible but couldn’t avoid showers that meant the Mercedes wanted to spin its wheels all the way through first, second and into third gear.

AMG claims that this car can reach 62mph in 4.1sec and the Shooting Brake in a leisurely 4.2sec. We managed only 5.2sec to 60mph in the coupé, but given that we spent half of that time reaching 30mph, we don’t doubt the 4.1sec claim one iota.

The V8 idles smoothly and menacingly and growls like the best of them on full throttle

Despite the tardy start, our test CLS posted a sub-10.0sec time to 100mph and had no trouble running into its 155mph speed limiter before we needed to brake at the end of MIRA’s mile-long horizontal straights.

Make no mistake: the CLS 63 is comfortably in the top division of saloon performance.

Given the hindrances to its standing-start performance, the in-gear figures make for more representative reading. To reach 70mph from 30mph takes just 3.6sec, and 5.6sec in fourth gear. Fourth is good for adding 20mph to your speed in less than three seconds all the way to 110mph. Third gear can add 20mph in less than two seconds almost all the way to its limiter.

All of which would be impressive even if the engine wasn’t as breathtakingly charismatic as it is. It fires with a deep, bellowy woof (rather often in traffic, given that it has a stop-start system that must sound ludicrous to the outside world), idles smoothly and menacingly and growls like the best of them on full throttle. 

Presumably, the turbochargers muffle the exhaust sound a little, but given how good this car sounds from the outside, it can’t be by much. Neither do they spoil the throttle response a great deal. Only if you get caught at low revs on a track will you notice any lag.

The seven-speed gearbox just about gets the best from it. It’s a single wet-clutch automatic unit (which also sees action on the SL 63), and although it shifts intelligently if left on its own and is smooth in daily driving, it wouldn’t hurt if the paddles gave slightly quicker downshifts.


Mercedes-AMG CLS 63 S cornering

During the past decade, our favourite Mercedes-AMG model to drive has been, by far, the CLK 63 Black Series, and that was a limited-run, hardcore special. It’s to the CLS’s eternal credit, then, that the CLS 63 runs it close for driver engagement while retaining the rest of the traditional Mercedes-Benz and AMG package. 

Granted, the CLS 63’s ride is a tad fidgety over broken asphalt at low speeds, notably so compared with, say, a Jaguar XFR. But you can forgive it because of the way body movements are controlled at high speeds (the dampers are three-stage adjustable, but you won’t need to go near the stiffer two settings on the road).

There’s excellent chassis control at higher speeds

That fidget gives the car a slightly different, slightly more focused demeanour than the last generation E 63 AMG, but the CLS is more or less happy doing the things at which the E 63 excels, too: being a straight-line, 300-miles-in-three-hours autobahn specialist. 

What sets the Mercedes-Benz CLS apart is a much greater sense of agility. At 1910kg, the CLS 63 is no lightweight, with the Shooting Brake weighing in at 45kg more than the coupé. Yet AMG has tuned the electrically assisted steering to make it feel like it has fewer kilos to its mass. It’s a relatively light rack, with 2.5 turns lock to lock and instant response that gives it a sharp turn-in. It’s a neat trick but not without a couple of downsides: it’s easy to over-correct the onset of a slide and there’s precious little feel.

It’s not as direct and flighty as that of the SLS AMG supercar, but it makes this near-two-tonne saloon feel a lot like a sports car rather than, like some AMG saloons, a straightforward, old-fashioned hotrod.

All of which would be pointless were the CLS’s chassis not as capable as it turns out to be. There’s excellent chassis control at higher speeds, well judged ESP settings and enough grip and capability to make it a rapid point-to-point machine; an involving and engaging one, too.


Mercedes-AMG CLS 63 S

It is just as well the CLS 63 is a serious sports saloon, because Mercedes demands a serious price for it, and a signifcant premium over the outgoing E 63, with the new E 63 S expected to cost in the region of £83,000 - it will be £3k more expensive the four-wheel drive, 600bhp saloon.

It’s startlingly easy to add options you’ll think essential, too, albeit harder to chuck on it the £40,000 worth of our test car. 

We returned 19.8mpg overall and, despite its interstellar gearing, only 25.8mpg at a cruise

Nonetheless, the Mercedes-Benz CLS’s relative rarity will ensure that residuals are competitive enough, and running costs are acceptable.

None of the CLS 63’s rivals can match the claimed 28.5mpg and 230g/km offered by this new turbocharged engine, even if it fails to translate into a massive real-world difference.

We still returned 19.8mpg overall and, despite its interstellar gearing (seventh gear can’t be selected below 60mph), returned only 25.8mpg at a cruise. That’s only a touch better than par for the course, in our experience.

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Mercedes-AMG CLS 63 S rear quarter

Limited-run Black Series models aside, the CLS 63 S is arguably AMG’s best attempt yet to alter the dynamic character of the Mercedes model on which it’s based.

The standard Mercedes-Benz CLS is a fine car, but rather than just take its character and turn up the performance, AMG has created a sporting car with a character and genuine dynamic ability all of its own. 

The CLS 63 AMG is an unqualified triumph

Any concerns about the engine are unfounded. It has all the low-end shove we loved from the old supercharged ‘55’ motor yet retains the growly character of the naturally aspirated 6.2.

In all but details, then — chief of which is the price that AMG demands for a car that is only acceptably specified — the CLS 63 AMG is an unqualified triumph.

However, the CLS 63 S is starting to look long in the tooth, with the now defunct BMW M5 and E 63 set to be replaced this year, its time seems limited as these new hot saloons take performance and agility to a whole new dimension.

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Steve Cropley

Steve Cropley Autocar
Title: Editor-in-chief

Steve Cropley is the oldest of Autocar’s editorial team, or the most experienced if you want to be polite about it. He joined over 30 years ago, and has driven many cars and interviewed many people in half a century in the business. 

Cropley, who regards himself as the magazine’s “long stop”, has seen many changes since Autocar was a print-only affair, but claims that in such a fast moving environment he has little appetite for looking back. 

He has been surprised and delighted by the generous reception afforded the My Week In Cars podcast he makes with long suffering colleague Matt Prior, and calls it the most enjoyable part of his working week.

Mercedes-AMG CLS 63 First drives