Old school AMG fans - you know, the ones who believe Affalterbach products should only be of the eight-cylinder variety - must be shuddering at the sight of the new CLS 53. "An AMG with a six-cylinder engine AND an electric motor?" they must gasp, before running away in floods of tears. "What's next, an all-electric AMG?!". Well, yes, probably.
But that won't be for some time. For now, the CLS 53 lands as the first of a new wave of electrically assisted AMGs that will each slot beneath the more hardcore V8 63-series models of their line-ups. Well, actually the CLS 53 won't, because in order not to tread on the toes of the new V8-engined GT four-door (another AMG with, erm, four doors), the 53 is to remain the top dog AMG CLS. Pressure's even higher then.
Not that the 53 is lacking firepower. It's driven by Mercedes' new straight-six 3.0-litre engine and comes supported by two forms of forced induction. The first is a big-bore twin-scroll turbocharger that provides the majority of power, but in order to eradicate as much low-rev lag as possible, the six-cylinder's inlet port is also force fed air by an electric compressor before the real boost kicks in.
This double blower setup is constantly varying its inputs depending on demand (aka your throttle angle) and helps this 3.0-litre produce up to 435hp and 389lb ft of torque. But there's more to come. The first AMG to feature some form of electric drive uses 48-volt architecture to power an integrated starter/generator (ISG), which adds a further 22hp and 194lb ft through the car's nine-speed automatic gearbox. We all know how much effect such a system can have on performance and how instantaneous the responses of electrified powertrains often are. Question is, can such a setup be made to behave in the way an AMG should?
First, let's consider the rest of the car. It's a CLS, so it's humungous and laughably longer than your average British parking space. But it's also ultra-luxurious inside with bits of S-Class including that wide, twin-screen infotainment system that can be controlled via a touch pad on the centre console, a rotary dial or mini touch buttons on the steering wheel. Oh, and you're not short of theatre inside a CLS either, with subtle but stylish ambient lighting that includes ultra-cool jet engine-esque air vents illuminated with a glow that changes colour as your adjust the climate control (red for hotter and blue for cooler). Gimmicky? Perhaps, but it certainly adds to the aura of luxury, like those mood lights under a sauna bench.
That's all good then, but an AMG should feel like an AMG when you press the start button. AMG's V8s growl into life and even its outgoing V6 engine says good morning with a bark. In the CL3 53, this new straight-six does neither, instead settling into a low-volume, slightly rattly idle. Things improve vastly once you're moving, however, because there's a new sense of urgency not familiar to AMG models before this. That is, of course, the result of that new electric injection of torque, which gives the car the sort of lateral off-the-line acceleration you'd expect from a proper EV but thankfully comes accompanied by a silky six-cylinder tone. Admittedly, it remains fairly hushed in all modes apart from Sport and Sport+, when it becomes louder and is augmented through the speakers by a high-pitched gravelly hum. The exhaust also now snorts with upshifts - which are very quick in both auto and manual modes, by the way - and you can just about make out crackles from the tailpipes on the overrun, which is fun.
There's no doubt about it, the CLS 53 is rapid, picking up pace like a sports car half a tonne lighter and responding to steering inputs like one half its size. Where the car feels large and long in the city, it somehow manages to shrink around you when you crank it up, such is the chassis' reactivity. In isolation, the 53 feels more eager to follow your steering inputs than the BMW M5. There's little in the way of feel through the wheel's rim but weighting reassuringly increases with speed. That being said, the CLS 53 can't be made to change directions in the lairy manner of an M5 because its AMG driveline can't be switched into pure rear-drive mode. There's a clear rear bias - it's 100 per cent rear driven in normal scenarios - but the front axle always comes into play when there's slippage, making it almost impossible to initiate any gentle corner exit slides - unless, of course, the steering angle is great and starting speed low.
Worth noting is the effectiveness of the standard-fit air suspension, which does a fine job of keeping the body in check and in Sport mode feels well suited to British surfaces when moving at pace. Sport+ tightens the damping effect further to eradicate almost all body roll, but in turn this can make the car follow the crests and troughs of rolling roads too closely for comfort. On that subject, in Comfort mode the car feels very refined, even on broken city roads, with only subtle hints of the increased harshness over the regular CLS over rough ridges or drain covers. Not even 20-inch AMG alloys with tyres of up to 275mm width (rear) can cause any significant hindrance to ride or road noise.
The faults? The engine's soft-limiter cuts power for too long so you jolt forward in the seat when it kicks in. The adjustable suspension, gearbox and traction control buttons are tucked behind the touchpad on the wrong side of the centre console for a right-hooker, so you need to fiddle for out of sight buttons to find them. Plus, for some people, the car may also appear a little too restrained, what with it lacking any significant external or internal design feature to emphasise the power on offer. Although that could also be a major pull factor for buyers after discreet performance.
This, therefore, is a very good car in all senses of the word. Without a thumping soundtrack it doesn't get the pulse racing like the old CLS 63, obviously - in fact the character of its powertrain never really feels all that AMG-like at all. But that's because we're not used to this new wave of electrified Affalterbach machinery yet. This is a car that will beguile its occupants with rapid pace and ultra-luxury in a way no other AMG has done yet. So long as each 53 model doesn't kill off the option of a burly V8 alternative (in this case the GT four-door ensures that), having such an effective form of new AMG is surely no bad thing at all.
SPECIFICATION - MERCEDES-AMG CLS 53
Engine: 2,999cc 6-cyl turbo
Transmission: 9-speed automatic, four-wheel drive
Power (hp): 435@6,100rpm, plus 22hp electric motor
Torque (lb ft): 384@1,800-5,800rpm, plus 184lb ft electric motor
Top speed: 155mph (electrically limited)
Price: £74,050 (as standard; price as tested £78,615, comprised of Comfort package (Air Balance and Energizing comfort control) for £395, Driving Assistance plus package (Active blind spot and active lane keeping assist, Active braking assist with cross-traffic function, Evasive steering assist, Active distance assist, Active lane-change assist, Pre-Safe Plus and Impulse Side, Route-based speed adaptation) for £1,695, Privacy glass for £345, Wireless charging for £150, Cavansite blue metallic paint for £685, 20-inch five-twin spoke AMG allow wheels painted in black for £1,295)