Hot hatch thermometer hits furnace temperatures for this range-topping A-Class

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The second-generation Mercedes-AMG A45 still looks like a significant landmark in the evolution of the hot hatchback, even three years after its launch

Depending on how public opinion continues to view outlandish and excessive performance cars like this over the next decade, it may even turn out to be a high-water mark of a sort. With 416bhp on tap from its turbocharged four-cylinder engine, this is nothing less than the most powerful series-production example of its performance breed there has ever been. It is, in short, the very hottest hot hatchback in the world.

AMG Aerodynamics package brings the rear spoiler, extra diffuser blades and canards on the front bumper. It guarantees that the car won’t be mistaken for an A35.

The A45 S is more powerful and expensive even than the rarest, hottest and priciest cult ‘fast 4x4s’ of the past 20 years: the Subaru Impreza STI and Mitsubishi Lancer Evo. It joined the Mercedes-AMG showroom range at the same time as the Mercedes-AMG CLA 45 S, which is almost mechanically identical and allows you to choose a very similar driving experience wrapped up in the body of either a four-door coupé or as a Mercedes CLA 45 S Shooting Brake estate.

It may be the most powerful of its kind, but the A45 S is also, by some margin, the most expensive of its kind. When it launched in 2020, it cost from £50,570. With the addition of inflation and the subtraction of the entry-level trims, that has risen to an eye-watering £63,285. And that means, of course, the car very boldly takes the hot hatchback into direct value comparisons where it perhaps ought to fear to tread, against sports cars such as the Alpine A110, Porsche 718 Cayman and BMW M2 Competition. But then it also promises outright performance to make those comparisons surprisingly tough to call: 0-60mph in less than 4.0sec and nearly 170mph flat out.

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So the next few pages should tell you whether a four-wheel-drive Mercedes A-Class really can go that fast, out of the brochure and on real-world Tarmac; and, perhaps more important, whether the new A45 can transcend the limitations that typically bind hot hatchbacks and offer the driver appeal to rival the mid-engined sports cars and rear-driven muscle coupés that £60,000 would otherwise buy.


The A-Class range at a glance

Based on the Mercedes A-Class high-volume hatchback, the A45 S crowns a broad range that includes diesel, petrol and plug-in hybrid A-class options. However, the A45 S is far more customised than its range-mates, not least because of its entirely new, AMG-built engine.

Mercedes-AMG A35 4Matic302bhp
Mercedes-AMG A45 4Matic+*416bhp

*Version tested


7-spd dual-clutch automatic    

8-spd dual-clutch automatic (A200d, A250e, A35, A45


02 Mercedes AMG A45 S RT 2023 front cornering

Although it seems somewhat unlikely that Mercedes-AMG’s new four-cylinder M139 engine will go on to enjoy the same hallowed status as its old M156 6.2-litre V8, it remains a remarkable piece of engineering.

In the base Mercedes-AMG A45 alone (which isn’t offered in the UK), AMG has managed to extract 382bhp and 354lb ft from its 2.0 litres and four-cylinders – figures that rise to a frankly ludicrous 416bhp and 369lb ft in the range-topping Mercedes-AMG A 45 S model tested here. All told, that makes for a specific output of up to 209bhp per litre. A Ferrari 488 Pista’s 3.9-litre V8 manages 182bhp per litre, by contrast. Be in no doubt that the new A45’s motor is the most powerful turbo four-pot in series production.

Quartet of 90mm exhaust tips feature internal fluting plus an AMG monogram. There’s no hiding the fact that this is a proper AMG model

The process of extracting such puissance from what is a fairly small engine is incredibly complex. While still mounted transversely at the car’s nose, it has been rotated 180deg so that its newly designed turbocharger and exhaust manifold are now sited rearwards and the intake system sits up front for improved airflow.

That turbocharger now has roller bearings (à la Mercedes-AMG GT 4-Door Coupé) for improved responses and an electronically controlled wastegate sharpens things even further. Cooling has been dramatically improved and the engine’s cylinder linings are coated in the same friction-reducing Nanoslide material that appears in Mercedes-AMG’s Formula 1 engines.

There’s a trick two-stage fuel injection system to help improve engine flexibility and reduce consumption and emissions, too. Meanwhile, clever calibration work enables its 369lb ft to arrive between 5000rpm and 5250rpm, with the theory being that this ‘torque shaping’ makes for a more naturally aspirated style of power delivery.

Power is directed to the road via an eight-speed dual-clutch gearbox and AMG’s 4Matic+ all-wheel drive system. This can send as much as 50% of the engine’s torque to the rear axle, where a new rear differential with two multi-disc clutches – one per wheel – can distribute the entirety of that punch as it sees fit.mercedes-amg-a45-s-rt-2023-facelift-headlight

This has also enabled AMG to install a Drift mode to sit alongside the myriad of other drive modes that govern the A45’s powertrain and steering response, four-wheel drive, stability control programmes and, if your car has them, adaptive dampers. Suspension is by way of MacPherson struts up front and a multi-link arrangement at the rear.

Significant structural reinforcement aims to improve front-end torsional rigidity and response. The front axle is now wider too, a change that – along with dramatically flared arches, big-bore quad exhausts, a large Panamericana grille and AMG Aerodynamics package – makes the new A45 a far more aggressive-looking proposition than its immediate predecessor. At 1661kg on our scales (split 61:39 front to rear), it’s 80kg heavier as tested, too.

2023 saw the introduction of a subtle facelift to the whole A-Class range. Most versions, including the junior AMG, the A35, have received a dose of mild dose of hybridisation, and we've detailed those changes in our main A-Class review. The A45 remains mechanically identical, however, and its changes are limited to new LED headlights and taillights, a new steering wheel and a revised multimedia system.


09 Mercedes AMG A45 S RT 2023 dashboard

As foundations go, the standard Mercedes A-Class’s cabin was always going to lend itself well to hot hatches. In terms of style appeal, the base architecture starts things off strongly: the same stepped dashboard top remains, as do the turbine-style air vents in the centre fascia and the large twin screens of the MBUX infotainment system. However, for the Mercedes-AMG A45 in full-fat AMG Plus specification, material quality has been suitably improved too.

Expansive sections of brushed aluminium now wrap their way around the tops of the doors and across the dash, their metallic surfaces contrasting smartly against the glossy black plastic panelling that surrounds the air vents and populates the centre console. In Plus-spec cars, genuine leather upholstery replaces the combination of microfibre and man-made Artico leather on the AMG Performance seats and door cards, while eye-catching sections of contrasting yellow panelling and stitching further heighten the car’s visual dose of athletic intent.

The seats themselves are pretty firm and position you a bit higher in the cabin than you might like, but their ample bolsters keep you snug and provide good support, while there is plenty of adjustability in the steering column.

Drive modes can be swapped using the configurable satellite controls on the steering wheel, which saves groping around the centre console and keeps your eyes on the road for longer.

Functionality is good, too. There are plenty of storage cubbies dotted around front and rear, and head and leg room in the back are decent enough, at 690mm and 930mm respectively. The 370-litre boot, meanwhile, is the same size as the standard A-Class’s and 35 litres larger than that of the Audi RS3 Sportback, its closest conceptual rival.

The 2023 facelift of the whole A-Class range brought two main changes. The first is the loss of the trackpad for the MBUX infotainment system. We’ll discuss what that does to the usability, but Mercedes hasn’t exactly made full use of the space that’s been freed up in the centre console. Instead, you just get a tray that’s slightly too small for most phones.

The other change is the introduction of the new-style AMG steering wheel, with its extra-chunky rim and touch-sensitive spokes. It feels good in the hands, but those haptic surfaces are easy to actuate by accident. On the A45, the wheel also sprouts two satellite pods that quickly let you switch drive modes and adjust individual parameters. Given that there really are a lot of modes that genuinely alter the car’s dynamic character, that change is quite welcome.

Multimedia system

13 Mercedes amg a45 s rt 2023 infotainment

Mercedes’ MBUX infotainment system remains as impressive as ever in its application in the A45 S. The sharp graphics and fluid responsiveness of both 10.25in displays are big draws here, as is the slick integration with the wireless Apple CarPlay and Android Auto.

With the 2023, the A-Class loses the trackpad mounted on the centre console, and the shallow tray that replaces it isn’t as useful. Then again, it was never quite as intuitive as the rotary dial you’ll find in some BMWs, and the touch-screen interface is very logical. More of a sticking point are the touch-sensitive surfaces on the steering wheel, whose input response can be frustratingly inconsistent.

In addition to having satellite navigation, phone integration and DAB radio, the S models get the AMG Track Pace app as standard. This lets drivers record lap times and analyse driving data. The MBUX Augmented Reality function can be used to project a circuit’s ideal racing line onto the head-up display, although we didn’t get the opportunity to test this feature for ourselves.


19 Mercedes AMG A45 S RT 2023 engine

Like all full-fat Mercedes-AMGs, the A45 S has a ‘race start’ launch control system that requires you to use Race driving mode to access it. The way in which the car takes off under that all-corner, wheelspin-optimised electronic governance blends savagery and smoothness to remarkably addictive effect.

The bald numbers we recorded for the car are all suitably monumental – except, perhaps, for the most important one (0-60mph). On a slightly damp surface, the car hit 100mph from rest in just 9.3sec. The Audi RS3 Saloon we performance tested three years ago was more than half a second slower than that and a Honda Civic Type R was fully three seconds slower. The A45 S needed just 3.3sec to get from 30mph to 70mph through the gears, whereas an Alpine A110 needed 3.8sec.

Cross-country pace is limited almost entirely by your sense of social responsibility, because the car has excellent grip, traction, balance, composure and acceleration

This is, by almost any marker, a very fast car and justifies its price quite easily in simple performance terms. It narrowly missed the chance to prove itself a sub-4.0sec 0-60mph operator in those slightly imperfect conditions, though. Its fastest oneway run on the day was 4.07sec, but on a warmer, drier day, that showing would certainly suggest times starting with a three are possible.

The four-cylinder engine supplies plenty of audible theatre, which you can adapt and change a little using its various drive modes, and its angriest pops and whooshes are always entertaining to listen to. But if our performance numbers leave any room to doubt that it is, in every way, the dominant force you might have expected, then getting to know the motor first hand and in detail may not emphatically settle the question.

There is more than a hint of peakiness about the engine’s production of torque; to be expected, you might think, in light of the fact that it’s operating beyond 200bhp per litre. It doesn’t feel overboosted or troubled by turbo lag, but it’s enough to make you wonder just how much of that peak torque is available when you flatten the accelerator below 4000rpm. That’s not something you ever wonder about Audi’s rampant five-cylinder RS engine, which feels a deal more flexible than the AMG unit – and, almost anyone would concede, also sounds considerably richer and more characterful.

The eight-speed dual-clutch gearbox can make the car’s low-speed manoeuvring behaviour a bit erratic, but it works quickly at pace and its kickdown tendencies can be adjusted according to the chosen drive mode. Brake pedal feel is very good, and the car sheds speed strongly even in slightly slippery conditions, as our test results show.


21 Mercedes AMG A45 S RT 2023 front cornering

Those who subscribe to the idea that a driver’s car must first and foremost possess good steering will be pleased to hear that the A45 S makes a strong start. This set-up, which uses speed-dependent gearing, isn’t immune to deflection or the odd flicker of torque steer, but it develops convincing weight and prizes accuracy.

As you’ll find with AMG’s more serious, rear-driven models, there’s also a communicative vein of feel that makes it easy to guide and place the car with satisfying conviction on tight, twisting roads. By the standards of today’s hatchbacks, with their electrically assisted racks, this set-up ranks as one of the best, although fractionally more self-centring action would make it unquestionably the class of the field.

The next step in your journey of A45 S discovery is to find that roadholding is every bit as jowl-tuggingly adhesive as you would expect, given this car’s ability to cleverly apportion drive between its 245-section tyres. Aggressively turn in to corners and there is but a tiny slither of latency before the tall body responds, and even this chink in the armour is exposed only during extreme direction changes. Most of the time, the centre of gravity feels low, the car’s composure largely unflappable, with grip and traction the dominant forces.

Eight-speed dual-clutch automatic is so much better than the seven-speed box fitted to lesser 35 models. Shifts are far slicker and I didn’t find myself inadvertently banging into the limiter quite as much

But what about Drift mode, which throws as much of the engine’s torque to the rear outside wheel as possible? Despite the marketing campaigns, the way this – and all of the more aggressive settings for the AMG Dynamics chassis electronics – mostly manifests is not with armfuls of opposite lock but with an awesome level of neutrality. Through corners, the rear axle can snag the inside brake and push drive to the outside, which essentially eliminates understeer on the road but can sometimes result in glimmers of rotation that require only an opening of steering angle. Of more significance is that, even when driven within the limits of grip, the A45 S feels more involving, serious and sophisticated on the move than any hatchback counterparts, be they driven by both axles or only the front.

As with so many good driver’s cars, there’s more than one way to drive and enjoy an A45 S on a track. The car offers uncompromising grip, composure and high-speed stability when you go looking for outright speed but it can also be driven in a more expressive and ostentatious style if that fits your mood.

The car’s torque-vectoring four-wheel drive system feels more natural than the one in the old Ford Focus RS. Rather than seeming to pitch the car into bends as the Ford can sometimes do, the A45’s driveline allows for lots of mid-corner stability, confidence and feel. In most driving modes, it gently but effectively neutralises the car’s attitude under power.

Drift mode isn’t like disengaging the front driveshafts, but it does allow you to accelerate the chassis into oversteer around a tighter bend quite simply and then to maintain a longish slide so long as you keep positive steering angle applied.

22 Mercedes amg a45 s rt 2023 rear cornering

Comfort and isolation

Before you’ve even cast an eye over the improbably big numbers on the spec sheet, both the look and sound of the A45 S suggest it might not brook much compromise for everyday driving. And there’s some truth in this.

The heated AMG Performance seats bring a degree of supercar glamour to this hottest of hatches. They are firm but widely adjustable and supremely supportive, providing comfort over long distances. Large wheels, firm springs and firm suspension mounts mean road roar is inevitable, however, and anybody acclimatised to Volkswagen’s Golf R will find the A45 S a noisy, somewhat busy cruiser.

But as we’ve discovered, this AMG is not a Golf R rival, and when you consider the fearsome performance and more hardcore character of the A45 S, you realise relative usability is one of the car’s greatest strengths. With the dampers in Comfort, the ride remains resilient but rarely if ever is it punishing – even at town speeds, which is where the old A45 tripped up – and day-to-day, the car demonstrates the softer side of its split personality.

With the A45 S, you get a dose of normality that owners of the Renault Mégane RS Trophy and Porsche 718 Cayman must occasionally long for. The A45 S further impresses with the fine-tuning of its driving controls. Natural pedal and steering response at everyday speeds contributes to the overall ease of use.

Track notes

Mercedes amg a45 s rt 2023 track notes

As with so many good driver’s cars, there’s more than one way to drive and enjoy an A45 S on a track. The car offers uncompromising grip, composure and high-speed stability when you go looking for outright speed but it can also be driven in a more expressive and ostentatious style if that fits your mood.

The car’s torque-vectoring fourwheel drive system feels more natural than the one in the old Ford Focus RS. Rather than seeming to pitch the car into bends as the Ford can sometimes do, the A45’s driveline allows for lots of mid-corner stability, confidence and feel. In most driving modes, it gently but effectively neutralises the car’s attitude under power.

Drift mode isn’t like disengaging the front driveshafts, but it does allow you to accelerate the chassis into oversteer around a tighter bend quite simply and then to maintain a longish slide so long as you keep positive steering angle applied.


01 Mercedes AMG A45 S RT 2023 lead driving front

Whether or not you take serious issue with the £63,285 sum that Mercedes asks for the A45 S will come down to personal perception.

Some might consider that reasonably good value for a practical, 416bhp all-weather performance car. Others might simply laugh in disbelief at the prospect of paying more than £60,000 for what is essentially a hot hatchback on anabolic steroids – even one with a premium badge.

Mercedes-AMG has kept only one version of the A45 in the price list, and it's the previously range-topping 'Plus' that wants for almost nothing. Most paint colours cost £625. Are you brave enough to choose Sun Yellow?

At least that buys you the version with almost all the bells and whistles, including the adaptive dampers, the AMG Aerodynamics package and Burmester sound system that used to be optional. Since the 2023 facelit, the only optional extras are a number of paint colours (white and black are free) and the £1495 Driving Assistance Package, which adds adaptive cruise control with steering assist. However, it’s worth noting that you’d still be able to buy an Alpine A110, BMW M2 Competition or Porsche 718 Cayman S – all incredible driver’s cars in their own right – for similar money. The A45's most direct rival, the Audi RS3 is no longer available to order, but delivery-mileage examples cost around the same as the AMG.

As for fuel consumption, our test car averaged 31.1mpg overall and recorded 41.5mpg touring economy. Combined with its 51-litre tank, that latter figure makes for a theoretical maximum range of 466 miles. Be in no doubt, however, that when you take your A45 on a track day, it will drink fuel like the 416bhp monster that it is.


23 Mercedes AMG A45 S RT 2023 static

If the Mercedes-AMG A45 S does go down as the most powerful combustion-engined hot hatch in history, it will be worthy of its fame.

This potent 2.0-litre engine may not sing, but the performance it spawns is remarkable and there’s character in the heady power delivery, if not quite as much as we’d like in the exhaust note.

Perhaps the most impressive element of all, however, is how tractable and well mannered this complicated and brutally stressed driveline is when it isn’t being fully exercised.

Indeed, it’s the all-round usability of this package that will make A45 S ownership so tempting to many. Given its cast-iron control of the body at speed, the chassis demonstrates genuine compliance. The loss of half a star is only because, although the A45 S delivers more driver appeal than most hot hatchbacks, it is not quite up there as a £60,000 sports car.

As an ownership proposition, it must therefore be considered as a practical four-seater rather than just as a purist’s driving machine. That said, those in need of a supersonic hatchback should look no further.

Matt Saunders

Matt Saunders Autocar
Title: Road test editor

As Autocar’s chief car tester and reviewer, it’s Matt’s job to ensure the quality, objectivity, relevance and rigour of the entirety of Autocar’s reviews output, as well contributing a great many detailed road tests, group tests and drive reviews himself.

Matt has been an Autocar staffer since the autumn of 2003, and has been lucky enough to work alongside some of the magazine’s best-known writers and contributors over that time. He served as staff writer, features editor, assistant editor and digital editor, before joining the road test desk in 2011.

Since then he’s driven, measured, lap-timed, figured, and reported on cars as varied as the Bugatti Veyron, Rolls-Royce PhantomTesla RoadsterAriel Hipercar, Tata Nano, McLaren SennaRenault Twizy and Toyota Mirai. Among his wider personal highlights of the job have been covering Sebastien Loeb’s record-breaking run at Pikes Peak in 2013; doing 190mph on derestricted German autobahn in a Brabus Rocket; and driving McLaren’s legendary ‘XP5’ F1 prototype. His own car is a trusty Mazda CX-5.