Mercedes-AMG A 45 S 4Matic+ (2020) review
Ballistic performance meets superb handling for AMG’s pocket rocket, the new A 45 S.
Dave Humphreys
Dave Humphreys

Published on July 30, 2019

If you prefer to call these things pocket rockets rather than hot hatches, then the Mercedes-AMG A 45 S is the Saturn V of its kind. It's extraordinary to consider that it wasn't all that long ago that people were saying 300hp in a hatchback was too much. Oh, how the engineers in Affalterbach must have laughed, because they've somehow managed to extract 421hp from a turbocharged 2.0-litre engine and shoehorned it into an A-Class. What a time to be alive.

In the metal

You can have the new Mercedes-AMG A 45 in regular or A 45 S flavours, though the visual differences between the two are subtle. We're bypassing the former and going straight to the five-chilli A 45 S version here. Among the distinguishing features are larger 90mm diameter quad exhaust pipes. These sit either side of a diffuser marked out by two vertical twin fins, helping to suck the rear of the car down into the ground at speed. An angled spoiler on the top of the boot lid also generates some downward force. Alloy wheels of 18-inch diameter come as standard, with the option of 19-inch items. They need to be big to fit around the huge 360mm cross-drilled front discs and accompanying six-piston callipers.

If you want an even more aggressive look, there is an optional aero kit available from the factory. Included in this at the front, two sets of dive planes are affixed to the corners of the front bumper and join a new splitter. Rearwards, there is a larger rear wing, similar to the one featured on the previous-generation 'W176' A 45. The diffuser gains an extra blade with spoiler lips on either side. All of these extra parts come with a high gloss black finish and, while they may look like styling add-ons, the AMG engineers claim that they have a significant impact on the aerodynamic balance of the car, with increased downforce at high speeds.

As you might expect for such a model, the interior of the A 45 delivers the best of what's available in the standard Mercedes-Benz A-Class and adds some trick bits. The flat-bottomed and flat-sided steering wheel comes wrapped in perforated leather, but the optional Alcantara version is nicer again, complete with yellow twelve o'clock marker on the top. Larger paddle shifters have a quality feel to them and beneath the multifunction switchgear on the wheel are two additional controls. On the left are shortcut buttons that can be set up for the damper settings and active exhaust, or something else should you prefer. On the right is a rotary dial that lets you toggle through the different drive modes. Elsewhere, the broad double display setup of the MBUX infotainment system stretches across the top of the shallow dashboard. While it can show a lot of information, the high-resolution display also makes it easy to see what you're looking for at a glance.

Driving it

You can have all the engine power in the world, but if that can't be converted through the transmission into forward motion, then it's as good as worthless. The Mercedes-AMG A 45 S does indeed feel like it has all the power in the world. That's down to the marvel that is the 'M139' engine. It's an entirely new design that began development in 2013 and was borne out of necessity; the existing 'M133' engine that powered the then-current AMG A 45 simply wasn't going to fit in this latest A-Class generation. So a new turbocharged 2.0-litre four-cylinder engine was created with high-performance goals set. The result is this compact engine producing 421hp and 500Nm of torque. Let those figures sink in as you remind yourself that this is an A-Class hatchback.

So how does that power get down to the road? Though a new AMG Speedshift eight-speed dual-clutch automatic gearbox, along with the active and fully variable 4Matic+ all-wheel-drive transmission featuring AMG Torque Control. Power is distributed between the front and rear axles, with torque vectoring by brake on the front axle and a more advanced twin multi-disc clutch setup on the rear. These electronically controlled clutches offer total variability in power distribution across the rear axle.

The result is a car that's not so much a hot hatch, but a thermonuclear one. Not that long ago performance of this kind was the preserve of proper supercars. Cue up the launch control function (you'll need to be in Race mode) and it flings you through the 100km/h barrier in 3.9 seconds. It feels faster than that. And it keeps shoving you forward with serious force. Peak power doesn't arrive until 6,750rpm, which in any gear translates into extremely quick forward motion.

But it doesn't have to be like that. Dial everything back to the Comfort setting and the A 45 can be as docile as you like. Leave the exterior aero pack option box blank, go for a more subtle exterior colour and you'll have something that is stealthy enough to remain off most people's radar screens. It's no bone-shaker either, though the sports seats do provide limited amounts of comfort on any journey beyond a couple of hours.

However, this is a car that you will want to drive, and not on dull and boring motorways either. It doesn't just reward keen drivers; it delivers confidence by the shovel-load and at times will make you question what you thought you knew about physics. We mentioned acceleration earlier, but how this car gets on with things is massively impressive. Seemingly irrespective of speed and gear, as long as your right foot is down, you're hurtled to the next braking zone. That's when the big brakes scrub off speeds in a very controlled manner. But even if you turn in carrying a little too much speed the car just seems to grip, without even a hint of understeer. The way the transmission manages power delivery is excellent, too, seeming to do everything you ask of it without ever noticeably activating the traction control.

When you hook up a winding road section the reward is immense. The electrically assisted steering has enough weight to it to still be engaging. With so much power and equally so much grip it becomes easy to get into a very enjoyable groove, the car following your desired line almost telepathically such is the precision. For the more adventurous there is a Drift mode that more fully exploits the abilities of the rear axle. This setting allows for far greater slip angles at the rear and, talent and space permitting, enables this all-wheel-drive car to pull off some pretty convincing donuts. On private tracks only, obviously...

What you get for your money

We'll skip allotting a score here for now as the official pricing is yet to be announced by Mercedes-Benz Ireland, but going by the starting price of the 'junior' Mercedes-AMG A 35 of €59,245, it's entirely feasible that the A 45 will be nearing €80,000 when it arrives on our shores. No matter how rose-tinted your glasses are, that's a vast sum of money for a car of this size, but its performance and engineering does go some way to justifying the price. After all, the A 45 will out-accelerate the Mercedes-AMG GT Roadster to 100km/h, a car costing nearly €200,000.


The Mercedes-AMG A 45 S 4Matic+ may be seen by some as one of the junior models in a vast range, but there's nothing little about the performance that it offers. Only when you spend time driving it and exploring the boundaries of what it can do, does the price tag become justifiable. The beauty of cars like this is that, to the average person on the street, it merely looks like another Mercedes hatchback. But those who know will know.


Tech Specs

Model testedMercedes-AMG A 45 S 4Matic+
Engine2.0-litre turbocharged four-cylinder petrol
Transmissioneight-speed automatic, all-wheel drive
Body stylefive-door, five-seat hatchback
CO2 emissions189g/km (Band E, €750 per annum)
Combined economy34.0mpg (8.3 litres/100km)
Top speed270km/h (electronically limited)
0-100km/h3.9 seconds
Power421hp at 6,750rpm
Torque500Nm at 5,000-5,250rpm
Boot space370-1,210 litres
SafetyEuro NCAP rating for Mercedes-AMG A 45 
Rivals to the A 45 S 4Matic+ (2020)