Mercedes AMG A45 S: what is it?
AMG’s A45 S is among the most powerful hatchbacks in the world. It has so much power that calling it a hot hatch somehow feels wrong. Under the hood sits a 2.0-litre, four-cylinder engine that puts out a record breaking 421hp. Not 200, not 300, an incredible four hundred and twenty one horses, enough to embarrass a V8. This makes it a champion when it comes to specific output. And then, because it is turbocharged, with a watermelon sized turbo, it also makes a massive 500Nm of torque. Thrust, when you lean on the accelerator, as you can imagine, is just immense.
On the outside, the A45 S is clearly more aggressive than a regular A-Class hatch. There’s AMG big Panamericana grille up front, a big front airdam, side skirts, a rear spoiler and four large round exhausts at the rear that hit the spot. 245/35 Z rated Michellin Pilot Sport (4) S tyres fill the wheel arches.
On the inside, the A45 S is actually similar to the A35 sedan up front. You get sportier trim and the rear seats are placed a bit low, but what hits home is the Merc’s high-quality cabin. Standard features include dual 10.25-inch MBUX infotainment and instruments screens with AMG performance displays, a Burmester hifi audio system, and a decently sized sunroof. And of course you get AMG’s Dynamic package. Optional equipment gets you ‘advanced’ sports seats, which also include a heating, massage and memory functions, head-up display, a chrome exterior package, and driver assist systems like a 360-degree camera, lane keep assist and blind spot warning. But what’s it like to drive? Let’s get straight in.
Mercedes AMG A45 S: what’s it like at high speed?
Now first up, this isn’t a full review, far from it. We only got to drive the car on a high-speed track. But what it is, is a full-throttle review. Mercedes has lined up something rather special and allowed us to experience this car’s electronically limited top speed of 270kph in a safe environment. As you may have guessed, we are at the world-class NATRAX testing facility outside Indore, where the 11.3km high-speed bowl allows you to access speeds in excess of 200kph with consummate ease.
As we set off from the parking lot, the first thing that draws my attention is the raucous exhaust note. There’s no big chesty V8 rumble and those fruity pops and bangs AMG V8s are famous for are missing, but what you get in its place is an almost rally car-like blare, and that’s especially in ‘Race’ mode. It sounds gritty in the top end, snarls nicely as you cross 5,000rpm and it even sounds trashy and a bit OTT towards the 7,200rpm redline. Have to say I like it ...a lot.
The next thing that gets my attention is just how responsive the engine feels. On the out lap, I shift up early, just to see how it responds. What’s clear is that this is no heavily modded motor with a big turbo and massive turbo lag. Sure, there is turbo lag at low speeds, but what lag there is gets masked by the twin-clutch gearbox and short gearing, and then, when I put my foot down even at 2,500rpm, it just pulls in an urgent manner.
Even better is the fact that every time I flex my foot around 4,000rpm there’s an avalanche of torque that just seems to erupt from below the bonnet. And then after 5,000rpm the engine just seems to run away from you with a momentum all of its own, the A45 S feeling like it’s getting ‘sucked’ forward. The twin-clutch box snaps you into the next gear before you hit the 7,200rpm limiter and keep your foot down and it seems to accelerate like a rally replica. In fact, this feels more like an Mitsubishi Evo and Subaru Impreza rival than a VW Golf GTi rival.
Then, as I pass 200kph, I expect some slacking off in pace. And yes, compared to the larger E 63 S, there isn’t that same sort of energy and trust. But what still blows me away is that there is no big stretch and no strain as it runs up and head-butts the limiter at 270kph; roughly 280 on the speedo.
The A45 S also feels extremely stable; 200kph is no sweat and it feels rock-steady. You feel cross-winds a bit more as you cross 240kph, and then accelerate at these speeds and you do feel the car ‘shift’ a bit as you put the power down. Even the steering responds pretty well at medium and high speeds, and doesn’t feel overly aggressive as it does on some hot hatches. I won't be able to tell you how well it drives around corners, how well the Drift mode works, or what it’s like on everyday roads: that will have to wait for our full review.
What I can tell you is that the launch control is epic. All you have to do is shift to Race mode, put your left foot on the brake, get the revs up and launch! AMG claims a 0-100kph time of 3.9sec, and this feels quicker still. It’s just so easy to access and so much fun; traffic lights will never be the same.
Mercedes AMG A45 S: what’s it like under the skin?
So just how has AMG transformed a luxury hatchback into a pocket rocket. First up is the 2.0-litre engine that gets 421hp and 500Nm of torque. Interestingly, the engine just doesn’t dump the torque out to the four wheels, AMG has tuned the engine to deliver pulling power when it is needed most. This "torque shaping" shifts peak torque output up the powerband, so the maximum output is delivered at a relatively high 5,000-5,250 rpm. AMG engineers say this helps give it a power delivery akin to a naturally aspirated engine, and increasing torque at higher RPM makes the engine more free-revving.
In addition, on one hand, a new twin-scroll turbocharger helps give the motor plenty of responsiveness at low-engine speeds, and on the other, a high-power output in the upper RPM range. To help improve exhaust flow to the turbo, the exhaust manifold is divided into individual ducts that help feed exhaust flow to the turbine separately. The aim is to prevent the individual cylinder pulses from influencing each other negatively, overlapping load cycles. The result is extremely good responsiveness.
To improve responses further, the turbo gets roller bearings. These reduce mechanical friction within the turbocharger to a minimum, allowing it to respond more readily and reach its maximum speed more rapidly. When spinning at its maximum speed, the turbo put out a high 2.1 bar, another record for an engine of this type, and AMG has used an electronically controlled wastegate (exhaust relief valve) that allows the charge to be controlled precisely, especially when accelerating from partial load.
As you can imagine, the turbo must generate tremendous heat, and to cool it, AMG uses fresh air, oil and water. The concept is based on the principles and experience gained with the cooling for the turbochargers that are mounted in the hot-V of the current AMG 4.0-litre V8 engines.
On the inside, the engine uses a lightweight, forged-steel crankshaft and forged-aluminium pistons, and the cylinders are lined with Nanoslide to reduce friction. The engine uses both direct and indirect injection and the intercooler works, uniquely, in conjunction with the air conditioning system and a second condenser. So, this clearly is not an everyday four-cylinder engine.
Further downstream an eight-speed dual-clutch gearbox and AMG’s 4Matic+ system are used to send power to all four wheels. The system 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 can send power to either wheel. This has enabled AMG to install a Drift mode, along with the AMG Dynamics suite of driver assistance programs that work on steering response, the four-wheel drive system, and stability control in stages.
Apart from new springs, adjustable dampers and stout anti-roll bars, AMG has also rebuilt the front end of the hatch to make it stiffer. It has given the A45 S a wider track, larger wheel arches and big-bore quad exhausts, as well as a large Panamericana grille. The cool looking rear spoiler and cannards and spades up front however can’t be got on the car in India.
Mercedes AMG A45 S: first impressions
Mercedes-AMG A45 S is the most powerful hot hatch yet. Pound for pound it has the most powerful four cylinder motor around and with it, as we’ve experienced, raw pace that transcends the hot hatch genre. But is this superhatch worth the Rs 79.5 lakh Merc is asking for it? Just how much does it thrill you around corners, what’s it like to drive on our everyday roads and, importantly, should you consider a traditional sports car instead? These unfortunately are questions we can only answer once we do a full review. What we can tell you, and with a fair amount of certainty, is that there’s simply nothing like it. It’s loads and loads of fun and clearly worthy of AMG’s S badge. It’s that special.
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