Mercedes-AMG S63 E Performance review

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Is the most potent S-Class yet still recognisable as the luxury limousine of old?

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The straight-faced imbuing of its flagship limousine with comical gluts of propulsive force isn't an activity that Mercedes has ever shied from.

Many times, AMG hasn’t even been needed to apply the finishing touches: the Mercedes mothership was already on the same wavelength. Take the W220-generation S600L, whose V12 engine made 590lb ft of torque, even in 2003.

Nevertheless, one might look at the specification for the very latest in this lineage of extroverted S-Class models and wonder if Mercedes has started to lose its zeal for such projects. After all, the 4.0-litre twin-turbocharged V8 in the S63 before you makes ‘only’ 664lb ft, which isn’t a vast uplift on the old S600L and certainly isn’t a headline-making figure.

But hold on: there is the second half of the car’s name to consider. ‘E Performance’ alludes to the plug-in hybrid nature of the powertrain, and it's an electric motor working on the car’s rear axle that helps make this not just the most powerful S-Class to leave the factory but the most powerful Mercedes saloon full stop.

Figures of 791bhp and 1055lb ft take digesting, and there’s no doubt that the near-£200k Mercedes-AMG S63 E Performance – now the sole way to have an S-Class mit V8 in the UK – will be fast. Yet the more interesting question relates to how comfortably such performance can sit within the broader S-Class remit. Is this still a world-class limousine or just a pricey freak show? Time to find out. 

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DESIGN & STYLING

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Mercedes AMG S63 e Performance review 2024 02rear tracking

The last time an entirely new AMG-fettled S-Class saloon graced these pages, it housed a 5.5-litre twin-turbo V8 that, curiously, developed precisely the same torque figure as the hand-built 4.0-litre unit in this, its successor, although it did so 250rpm earlier, at 2250rpm.

Of course, the 2013 S63 didn’t have a 236lb ft rear-mounted electric motor to help it along, and neither did it have front driveshafts (at least, not in the UK), active anti-roll bars, active engine mounts or rear-wheel steering, as the new car does. The W223-generation S63 duly moves the hot S-Class game on straight away, although it comes at a cost.

With 88 litres of super on-board, our test car tipped the scales at 2666kg, making it heavier than even a V8-hearted BMW X7 seven-seater. The sheer amount of hardware towards the tail of the car – 13.1kWh battery, electric motor with two-speed gearbox and, of course, electronically controlled limited-slip differential – shows up in the distribution of weight, which unusually for a front-engined car has a pronounced rear bias (46:54).

Note also that the battery has been developed with Brixworth-based Formula 1 engine maestro Mercedes-AMG High Performance Powertrains. It's designed for fast discharge and recharge cycles and is maintained by 14 litres of coolant.

Moreover, because the motor bypasses the nine-speed gearbox attached to the V8, the full torque potential of both engine and motor can be utilised simultaneously. The 13,500rpm motor can feed 236lb ft to the rear at any point in the V8’s rev range.

Elsewhere, the electronically controlled clutch pack dictates the torque split of the 4Matic+ system and can channel V8 and electric power to the front as required.

The S63 also gets its own tune for the dampers and air springs, some underbody bracing and composite brake discs – 400mm at the front.

INTERIOR

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Mercedes AMG S63 e Performance review 2024 07dash

The S63’s cabin is relatively demure and an Alcantara-trimmed steering wheel is about the only obvious giveaway that the S-Class you have just boarded might be a little out of the ordinary.

We like this but would have preferred a slightly richer hue to the perforated, quilted leather than the black of our test car. Sienna Brown and Carmine Red are no-cost options.

When it comes to rear seats, while this car will officially crack 62mph in a little over three seconds, it hasn’t forgotten what’s at its core. As standard the S63, comes with the Chauffeur Pack, which allows the front passenger seat to move unusually far forward, and small touches such as the feather-soft headrests, heated armrests and extra-plush seatbelts make the back of an S63 a sublime place in which to while away miles.

Electronically deploying shades for the windows and rear screen can also provide a cocooning environment on a whim, and there’s a panoramic roof to achieve the opposite effect.

Boot space is poor, mind, and falls from 540 to 305 litres because of the battery pack. Both the Audi S8 and BMW M760e have 500-plus litres.

ENGINES & PERFORMANCE

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Mercedes AMG S63 e Performance review 2024 18 engine

Seeing as we are dredging up comparisons with members of AMG’s extensive back catalogue, here’s another one: this S63's recorded 0-100mph time of 7.1sec is nearly a second and a half quicker than that of the then £249,500 SL 65 AMG Black Series of 2009, a no-compromises, fire-breathing Mercedes supercar of the first order.

If that’s a bit abstract, consider that the 30-70mph time in kickdown is just three-tenths shy of the time recorded by the thunderous, five-star BMW M5 CS, only recently retired.

It’s unsurprising that the S63 is an enormously rapid saloon, and it feels so even when you don’t call on its full potential. There’s a palpable depth to its reserves, even if you’re only indulging in a little gentle roll-on acceleration in Comfort mode. The electric element of the powertrain is partly responsible for this, as it gives the big saloon an unusual alertness at all times, yet this never spills over into sensitivity.

If you do need to kick down, the gearbox shuffles itself quickly enough, and shortly thereafter you are, in essence, riding a 5.3m rocket, although the S63 disguises road speed eerily well.

Gearshifts are normally slickly executed if the powertrain is under reasonable load, and as you ramp up through the modes, of which Sport+ is the most aggressive, the car will even cut ignition to hasten shifts and maintain momentum with torque fill from the electric motor. It’s an effective technique, although with so much torque in play in general, the delivery often has an EV-esque uniformity to it, even if the slightly repressed V8 woofle – both real and manufactured – never lets you forget what’s ahead of you.

The delivery is more impressive than it is lovable, though. It’s also not infallible. On more than one occasion our test car elicited driveline shunt, particularly at low speeds, that has absolutely no place in a world-class limousine, red-hot or not.

This hybrid driveline is also noisy at times, clicking and clunking in a way that makes the car feel fragile, even if it is just business as usual mechanically.

Our final complaint is that the topping of electric torque that sits on a bed of V8 grunt is not always sensitively delivered. The boost provided by the motor comes and goes, with no relation to the shape of the engine’s efforts. The result is fast, sure, but it’s also a bit unsettling.

RIDE & HANDLING

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Mercedes AMG S63 e Performance review 2024 20 side panning

The fact that this car is a PHEV, and that it has almost as much power as the Ferrari 296 GTB, will be the talking points, but arguably the most impressive thing about the S63 is the way it handles.

It often feels much like an overgrown C63, thanks to the amazingly linear steering, the inherent chassis balance and the ability of the suspension to resist deflection and general upset, which paves the way for two axles to act as one in a way they have no right to, given the distance between the car’s domineering nose and its quad-piped tail. Mercedes proved it had the measure of orchestrating numerous complex chassis systems with the AMG GT 4-Door Coupé, and the same expertise has evidently been brought to bear here.

Short of a Bentley Flying Spur, there is no luxury limousine that's quite so collected when you point it down a half-decent stretch of road. It isn't just possible but in fact exceedingly easy to drive this S63 very fast; to have the confidence to place the car precisely where you want it.

This necessarily comes at the expense of some flair. So epic is the physics involved when the S63 is in full flight that adjustability has been sacrificed. The car is quick to amp up front-axle drive, and the ESP system is quick to intervene, even if the AMG Dynamics control is set to the dubiously named Pro. It seems odd to bemoan the fact that such a large car is reluctant to misbehave a little. But then again, we only rue the fact it hasn’t been allowed to do so because it's clearly so capable and has the potential to reward.

Still, there is plenty of satisfaction to be had in flowing the S63 along at a good lick.

Brake pedal feel isn’t bad either, despite there being a generous regenerative element.

Comfort & Isolation

In the broader sense, the S63 is superbly refined. It has an effortless waft in its most relaxed state and the material comfort of its cabin only enhances matters. For the driver, visibility is also very good.

That said, AMG-ification has clearly had a detrimental effect on the soporific quality of the S-Class. Its large wheels, performance tyres and optimised suspension bushings make it noisier than we would like, especially on pitted surfaces. The 68dBA recorded at 70mph compared poorly with the Flying Spur’s 64dBA and the comparatively whisper-quiet 62dBA of the S580e that we tested in 2022.

Secondary ride is also below par, the S63 failing to absorb potholes and drain covers with the insouciance expected of such a car. This is an age-old concern for AMG-fettled S-Classes, and while this latest iteration achieves the best marriage of speed and tranquillity yet, it’s still not wholly convincing.

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MPG & RUNNING COSTS

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Mercedes AMG S63 e Performance review 2024 01front tracking

The £190k S63 is more a statement than a luxurious tool, as the excellent S400d diesel is. Therefore don’t expect the hybrid element to be transformative for the car’s economy.

The figures below were taken with the battery depleted, which is how owners will often find it, unless they are driving limited miles in urban areas and charging regularly. Even then, expect fewer than 20 miles of electric range on a full charge.

As for rivals, Audi and BMW build an alternative to the S63, but its finest foe is sure to be the new Flying Spur Hybrid, which we will test soon.

VERDICT

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Mercedes AMG S63 e Performance review 2024 22 front static

If anybody has the right to bestow near-comical levels of power upon an unsuspecting limousine, it's AMG – creator of the legendary Red Pig.

Here, its latest effort doesn’t disappoint in matters of straight-line speed or cross-country pace. The S63 is remarkably easy to drive quickly and at times remarkably enjoyable and poised for a car of nearly 2.7 tonnes and 5m in length.

However, the compromises made to achieve this are simply too great. In S63 guise, the S-Class loses too much rolling refinement, and at times its PHEV powertrain is also lacking in basic finesse.

Richard Lane

Richard Lane, Autocar
Title: Deputy road test editor

Richard joined Autocar in 2017 and like all road testers is typically found either behind a keyboard or steering wheel (or, these days, a yoke).

As deputy road test editor he delivers in-depth road tests and performance benchmarking, plus feature-length comparison stories between rival cars. He can also be found presenting on Autocar's YouTube channel.

Mostly interested in how cars feel on the road – the sensations and emotions they can evoke – Richard drives around 150 newly launched makes and models every year. His job is then to put the reader firmly in the driver's seat.