Four hundred and twenty one horsepower. Sheesh. That’s four times the output of a Mk1 Golf GTI and more than twice what a Fiesta ST could muster. It’s also enough to defeat a Ferrari 288 GTO (arguably the first hypercar ‒ discuss) in a game of Top Trumps. The Mercedes-AMG A45 S isn’t just a hot hatchback. It’s boiling over.
Aufecht, Melcher and Grossaspach (AMG) is a brand built upon stonking V8s, so the original 381hp A45, launched in 2013, felt like a gamble. Yet it paid off handsomely, blitzing all-comers in a straight line, doubling its sales target and bringing forth a range of four-cylinder AMG models. Now even the larger V8 models are halving their cylinder-count.
Recently updated for 2023, the latest A45 S is no ordinary four-pot firecracker. Beneath its bonnet lies the most powerful production four-cylinder engine… (pauses for Clarkson-esque effect) …in the world.
Small and mighty
Extracting a higher specific output than the 8.0-litre W16 in a Bugatti Chiron isn’t simply a case of cranking up the boost. The 2.0-litre motor in the A45 S uses a roller bearing turbo with an electronically controlled wastegate, two-stage fuel injection, F1-style Nanoslide cylinder coatings, enlarged exhaust valves, an aluminium crankcase, a baffled sump and separate cooling systems for the cylinder head and block.
Each engine is hand-built in Affalterbach and bears the signature of the man or woman who assembled it – just like those thunderous and much-loved V8s.
It all hits the road via an eight-speed twin-clutch gearbox, two limited-slip differentials (mechanical at the front, electronic at the rear) and four-wheel drive. The result, in a five-door family hatchback, is 0-62mph in 3.9 seconds. A 288 GTO wouldn’t get close.
There is another startling number to process. At £63,285 for the A45 S Plus (now the only version available) this hot hatchback is priced within the realm of ‘proper’ sports cars, such as the Alpine A110 and Porsche 718 Cayman. For that kind of cash, it needs to offer more than just pub bragging rights.
The physical limits
It certainly looks the part, especially in the matte grey of my test car (see embedded tweets). The front bumper sprouts a splitter and race car-style flics, while the rear arcs into a brutal diffuser and four meaty tailpipes. Forged 19-inch alloys surround huge six-piston brake calipers, painted bright red with black AMG lettering. And a gloss black spoiler is perched atop the tailgate, said to ‘increase handling stability at the physical limits’.
If all that isn’t exotic enough, the swoopy Mercedes-AMG CLA saloon and CLA Shooting Brake estate offer the same 421hp firepower with a splash of extra style. You’ll pay around £5,000 and £6,000 more respectively.
Whichever body style you choose, you get the same space and practicality as the standard vehicles. This isn’t a Nurburgring-record special edition with a chassis brace instead of a rear seat. Its 395-litre boot is on par with a Volkswagen Golf.
Tech for the track
It speaks volumes for the ultimate A-Class that, even on the far side of £60,000, you don’t feel short-changed by its interior. Most surfaces are swathed in supple leather or brushed aluminium, garnished with racy yellow highlights and 64-colour ambient lighting (because 63 shades just isn’t enough). The AMG Performance seats look fantastic and lock your hips firmly in place, although I’d welcome a bit more padding.
As beneath the bonnet, there’s a tonne of technology here – and getting acclimatised takes time. The dashboard is dominated by two 10.25-inch widescreen displays, configured via fiddly touchpads on the steering wheel or between the seats. The graphics are super-sharp and an array of performance data is available, alongside Apple CarPlay and Android Auto connectivity.
One interesting feature is the AMG Track Pace app, which maps out more than 60 real-world racetracks – including the Nurburgring – and records your lap times, plus full telemetry data. You can even use the head-up display to show braking points, track position, the radius of the next bend and more. It’s the next best thing to having your own pit crew.
In the past, big-boosted four-cylinder engines suffered with chronic turbo lag, then demanded an oil-change every other month. No longer. The A45 S punches hard throughout the rev range, and its service intervals are every year or 12,500 miles. It feels unburstable.
Nonetheless, it’s wise to limit your number of maximum-attack getaways, if only for your stomach’s sake. Select Race mode via the Porsche-style dial on the steering wheel, activate launch control, bury your right foot and… BLAM! With instant all-wheel traction, fierce power and super-quick upshifts via the paddles, it squeezes your internal organs so hard you forget to breathe.
It sounds nothing like an AMG V8, obviously. But the whooshes, fizzes and pops of this highly tuned engine – rortier and ruder in Sport and Sport+ driving modes – can’t help but raise a smile.
Power and control
So, having lapped the Nurburgring like a pro and embarrassed Ferraris at the traffic lights, it turns out the A45 is pretty nifty on a B-road, too. Indeed, as a means of joining the cross-country dots, in all seasons and all weathers, few cars are so crushingly capable.
There’s a limit to how quick you can go on Her Majesty’s Highway, of course, which is where the less exuberant Audi RS3 falls slightly short. Yet the Mercedes is fun at sane speeds. Its steering is lucid, turn-in is aggressively direct, body control is unwavering and the brakes feel mighty. You’re in the thick of the action, rather than watching from the sidelines.
The 4Matic+ four-wheel-drive system also joins the fun. Like the now-departed Ford Focus RS, it uses torque vectoring to create a rear-biased feel and effectively quash understeer. Also like the Focus, there’s a controversial Drift mode, which amplifies up this effect by channeling torque to the outside rear wheel.
Either way, this is no tyre-smoking C63 wannabe. My overriding impression was of superb balance and reassuring neutrality. Oh, and speed. So much speed.
The ultimate hot hatch
The price paid for such dynamic acuity is a very firm ride, not helped by those unforgiving seats. I could live with it – and if you’ve read this far, I suspect you could as well – but it would put me off running an A45 as a family car. A Golf GTI does that job better.
In truth, the A45 S is closer in spirit to heroes of yesteryear like the Subaru Impreza Turbo and Mitsubishi Lancer Evolution. It’s a giant-killer, a car that makes fast work of, well, everything. Even at £63,285, it offers a substantial amount of performance per pound.
Above all, it’s a riot to drive. A sports car such as the Porsche Cayman inevitably offers a purer, more nuanced experience, but if you want the ultimate hot hatchback, look no further.