We all knew that there would be inevitable casualties among performance car engines as the car industry marches relentlessly towards electrification, but who would have guessed that some of the earliest would come from AMG?
The high-performance arm of Mercedes-Benz built its legend on hi-po V8s and sixes, so you would think it would have wanted to hang onto them for as long as possible, paying lip-service to electrification by slapping 48-volt mild hybrid systems on them just to keep people happy.
But no – AMG has fully embraced electrification. And, of course, the serious performance that partnering hybrid-boosted systems with forced induction can bring.
Fortunately, AMG had a pretty serious 2.0-litre turbocharged engine it could base this approach around in the form of the M139 engine found in the small-but-mighty A 45 S.
The M139 engine springs from the same “one man, one engine” hand-built philosophy as AMG’s iconic V8s and boasts some ballistic-level power numbers: 285kW/480Nm in standard guise and 310kW/500Nm in 'S' guise.
You would think AMG would have wanted to hang onto V8s for as long as possible, paying lip-service to electrification by slapping 48-volt mild hybrid systems on them just to keep people happy.
So to replace the six-cylinder 43 models, AMG has reworked it and slapped on a mild-hybrid system that ups those impressive base numbers to 300kW/500Nm. While this is 10kW down on the 'S' variant of the A 45 we get here, you do get a 10kW 'boost' from the 48-volt system that adds some extra low-end response.
While for the V8 63 models get an even madder plug-in hybrid system that adds a second electric motor and some truly insane numbers: 545kW and 1020Nm.
But it is that middle child we are looking at today, with the first C 43 to drop the six in favour of a four.
The C 43 is every bit a high-spec C Class, with a high level of standard equipment, including Mercedes’ thoroughly excellent adaptive cruise control. The interior is likewise standard C Class, with some slick AMG sports seats, coloured stitching and subtle badging. Nothing too in-your-face here, except for the standard Benz interior ambient lighting, that is...
On the outside, things are muscled up a bit, but still lean towards discretion, just so as to not muscle in on the C 63’s territory.
This is all accompanied by a feral roar which has tones of V8, with the unmistakable growl of the A 45’s ICE, as well as a gruff, feral edge that is quite unlike anything else.
But all of that is expected and totally irrelevant here, because all anyone wants to know about the C 43 is what the new powertrain is like. Hell, it’s all I was interested in. 
It is easier to break the response to that question into two parts of the powertrain: the engine and the transmission. Because, well, it is a mixed bag...
Starting with the good – the engine is superb. Like most performance hybrid set ups, the electric motor perfectly complements the turbo engine by filling in any turbo lag off the line and then assisting whenever it is needed anywhere else as well.
This delivers a seamless tsunami of power literally anywhere in its rev range that pins you back in your seat whenever you push the throttle pedal to the floor. This is all accompanied by a feral roar which has tones of V8, with the unmistakable growl of the A 45’s ICE, as well as a gruff, feral edge that is quite unlike anything else. 
Fortunately, like everything else with the M139 ICE turbo four, it is also superbly capable of behaving in a civilised manner at urban speeds, perfectly happy to potter around just like a normal car.
This delivers a seamless tsunami of power literally anywhere in its rev range that pins you back in your seat whenever you push the throttle pedal to the floor.
Unfortunately, that brings us to the other part of the powertrain that is not so great – the transmission. 
Actually, to be fair, the transmission is a very good unit, but it just doesn’t play all that nicely with the engine. While the A 45 uses an 8-speed dual clutch transmission, the C43 uses AMG's version of Benz's standard 9-speed auto, but swaps out the torque converter for a compact multi-clutch set up which is very slick and super-fast at switching cogs when you are hammering it along. But it is that pretending to be a normal car at urban speeds thing that trips it up.
Asking the transmission to shift down a few gears at low is surprisingly slow and, as a result, often makes driving the C 43 around town jerky and frustrating, with the overwhelming feeling that hooking the engine up to a conventional torque converter automatic (or even the A 45's DCT) would have made for a much better experience.
While you might normally give a feral performance sedan a pass for a slightly awkward transmission at low speeds if it does the job when you are giving it the beans, the C 43’s reason for existence is to bridge that gap between feral performance and civilised daily driver.
And that is something that the transmission just stops from happening. Which is disappointing.
The Mercedes-AMG C 43 is a startling achievement in squeezing big power out of small displacement using lots of technology, so it is a shame that its everyday usability has taken a hit because of the transmission. Still, if you just want a furiously fast performance sedan and only care how small the time between standstill and the speed limit is, then the C 43 is hard to beat.
Until the C 63 arrives, that is.
BREAK IT DOWN
MERCEDES-AMG C 43
ENGINE: 2.0-litre turbo petrol hybrid
POWER: 300kW/500Nm
GEARBOX: Nine-speed automatic, AWD
PRICE: $149,500
PROS: Powerful and flexible engine, fantastically aggressive sound, typically superb Mercedes quality
CONS: Transmission frustrating at urban speeds, haptic steering wheel buttons a pain, they could've squeezed a bit more power out of it...
