Mercedes-AMG A 45 S 415bhp Of Four-Cylinder Fury

Take an A-class, add the world’s most powerful series-production four-cylinder engine and throw on some GT car aero and you get this: the AMG A45 S. Sitting above the A35, it’s Affalterbach’s ultimate hatch – and it’s the latest example of the ‘hyper-hatch‘ trend we’re slowly becoming used to.
 

Making 415bhp with a 0-62mph sprint of under four seconds, the A45 S puts Affalterbach’s performance know-how into what’s essentially a family run around. And with electrification looming on all sides, it may be one of the last cars to deliver old-school AMG theatre as we know it. But is it any good? We’ve driven it at length to find out.
 
Should I buy an AMG A45 S? If you want one of the best hot-hatches around, then you could do much worse – though a Honda Civic Type R offers a purer experience. Do you need 415bhp, though? Really?
 
What’s new?
You’d be forgiven for not spotting the differences between this version and its predecessor. Exterior tweaks are minimal: there is a slight difference in the headlights – most apparent in the daytime running light signature – but otherwise you’re going to need to get close enough to spot that the small round badge on the top of the nose is now the Affalterbach AMG logo rather than a Mercedes emblem. After all, the A45 S doesn’t need to shout any louder than it already does.
 
The interior gets a refresh, but other than the A45 S has been given a relatively light upgrade.
 

What are the specs?
AMG’s engineers have somehow eked out over 400bhp from a 2.0-litre four cylinder lump, helped in part by a turbo. The result is impressive: as well as 415bhp, the motor makes 369lb ft – albeit at a relatively heady 5000-5250rpm. Top speed is 168mph, which you’ll need a track or autobahn to truly experience.
 
This is not a classic front-wheel drive, hot-hatch, though and you will not detect any signs of lift-off oversteer. The A45 S puts it power out via an eight-speed twin-clutch auto – with paddles, of course – and powers both axles. Both rear wheels are individually clutched, which certainly helps when laying down the power. We’ll get into that later.
 
What’s it like to drive?
This car may feature some interesting engineering, but it leaves you to do the driving thankfully. Instead of any frustrating sense of the front end being held in check, there’s a deliciously rear bias to the way this car leans into the tarmac, leaving the steering crisp, responsive and engaging. The sophisticated electronics underpinning all of this, tweaking individual brakes and balancing torque, carry out their interventions like guerrillas in the night, barely detectable.
 
Mis-time your upshifts in manual mode and you will get mildly punished for it, however. In the first few gears acceleration is so fierce it’s easy to get trapped on the limiter. Flatten your right foot from a standstill and it feels almost electric car fast (0-62mph takes 3.9sec) but snap the throttle on and off because you’ve hit the redline and the A45 threatens to start pogoing – forcing even this small amount of finesse a reminding difference between conventional performance and the single-gear effortlessness of electric drive.
 
The soundtrack is equally key to the A45 S experience. Mercedes-AMG’s four-pot may not quite match the charisma of the RS3’s five cylinders, but it’s still a finely honed mechanical opus. Capable of smoothly refined moderation if required but a snarling buzzsaw that crescendos handsomely whenever you need to make an impression, it’s supported by an exhaust tune that runs the gamut from demure in Comfort through to artillery fire in Sport+.
 
As you’d expect, the ride is on the firm side, though it’s not unbearable. s with the powertrain settings, Mercedes has managed to resolve a real breadth of character across the three suspension control modes available from the AMG Ride Control adaptive damping system.
 
You’re never not in a performance car, but you’re also never left feeling like you’ve had to pay a severe penalty for that privilege. The quality of the seats seems to help. We haven’t crossed continents in this car, but we have spent entire days at the wheel with no immediate reason for complaint.
 

What’s the interior like?
Like other Stuttgart creations as of late, the A45 S interior treads a fine line between techno boudoir and modern good taste. There’s a ‘trendy’ (Mercedes’ word, not ours) new sage grey finish available for the seats, and the yellow accenting remains surprisingly acceptable – combine with the purple ambient lighting option to create some kind of near-future manga vibe, which works neatly with the skinny expanse of abutted screen for infotainment and instrumentation.
 
The steering wheel dodges the overly fiddly touchpads of some modern Mercs, and the touch-slider it retains for media volume is entirely useable. There are a host of other controls integrated into the wheel – which is a feast or glut of tech, depending on your tastes. Many of these can be worked out on the fly – but most fun of all are the iconographically illuminated and customisable AMG buttons.
 
Grafted on in their own individual pods, the one on the right twists – ideal for cycling through driving modes – while the one on the left is split in two allowing you to instantly access a variety of other functions such as ESP status or exhaust volume. We had the top half set to control the AMG dynamics settings, the bottom the transmission.
 
There’s plenty of tech, though: the MBUX infotainment system is deeply slick by appearance and genuinely not too difficult to get your head around when you have a moment to reflect upon it. But when travelling at the kinds of speeds the A45 S is capable of, it’s often easier to use the voice control, which has stepped up a notch or two.
 
Before you buy
AMG’s hot-hatch has evolved and so has its rivals. It now goes up against natural competitors such as the Audi RS3 and the VW Golf R – as well as the BMW M135i xDrive. Let’s start with the Audi.
 
Ingolstadt’s hot-hatch is a hair’s breadth faster hitting 0-62mph in 3.8- to the A45 S’ 3.9 seconds. It’s got the Mercedes beat on the top speed too, edging it by 6mph more at 174mph. The interior, while a little less extreme may be more palatable for some as well.
 
However, most important is the Audi’s five-cylinder turbo which sets it apart from the Mercedes – and every other car on the road. And although it lacks the ultra-precise feel of the AMG, a five-cylinder will always be a class above an impressive four-cylinder.
 
The Golf R is a bit further behind performance-wise, but does so at a price which is a solid £20,000 below this car. It’s also a bit less special. The BMW should also get a mention; it’s big on practicality but falls short in engagement to the other cars here.
 
Much of the A45’s competition comes from its smaller A35 sibling, which does a sensible amount of what the flagship does – and for a more sensible price. Starting from £45,930 it’s almost around £20,000 less than its larger brother but is still quick on paper: 316bhp, all-wheel drive and a 0-62mph sprint of 4.7 seconds is hardly slow, is it?
 

Mercedes-AMG A45 S: the CAR verdict
The A45 S exudes an exacting fitness of purpose. It’s tightly proportioned and easy to thread between most obstacles yet can still carry four adults – and their luggage – if required. The interior and its control systems are high quality and modern but unintimidating, and you can always talk to it if you get confused. The augmented reality directions make a good case for sticking with the built-in sat-nav, too, rather than defaulting to Carplay or Android Auto.
 
Meanwhile, the ride is compromising enough to make going the distance an unflinching affair. And although the big and bold performance is a huge element in the mix here, it never risks overwhelming the rest of the car, so fundamentally well sorted are the other aspects of the driving experience.
 
CAR has always liked this version of the A45 S, and with so little changed for the facelifted model there’s no reason to start rowing back from that now. Rather, the things we took issue with originally – the erratic voice control and overly complex infotainment system – have now matured, leaving terrifyingly little to fault here.