Mercedes A45 AMG S Review

Mercedes-Benz AMG A45 S

The car that recently caused some controversy after Chris Harris gave his honest opinion on Instagram which went against the majority of motoring journalists and called out the ‘influencers’. Harris referred to it as the ‘Most disappointing modern AMG I’ve driven.’, he went on to explain how it understeers badly, the brakes don’t hold out long and then went on to drop the remark ‘Built to please influencers on a launch event, which I gather it did’. Harris is one of the most respected car journalists in the industry, it is likely Harris has just told it as he sees it, but it has had a number of people questioning if this was more of a dig at influencers with the car becoming collateral damage. We want to form our own opinion though, so let’s take a look at what we know so far.


The internal combustion might not be the future, but we still drive petrol and diesel cars, so why should carmakers stop developing them? We have neglected fossil-fueled engines in the scramble toward EVs. And yet Mercedes, sensible and practical as they are, have gone back to their roots – they are building heat engines by hand and running them on petrol. None of their new motors are anything short of a masterstroke – the pinnacle of mechanical efficiency – the most powerful engine in its displacement class. The new A45 AMG S comes with one of them.


Mercedes-Benz AMG A45 SThe new M139 is an inline-four-cylinder. It is fed by a twin-scroll turbocharger. It wasn’t supposed to be – Tobias Moers wanted to have a twin-turbo setup. But AMG’s head of design, Ralph Illenberger, propounded that he could get the power and emissions from a single-turbo setup. The engine can take up to 160 bar of pressure and is capable of diesel-like compression, making it thermodynamically efficient. It has an intake at the front and the exhaust and turbo follow at the back. The turbo is cooled by water, oil, and air channelled from the front and through to the bottom of the car. The cooling system uses two electric and one mechanical water pump. The head-cooling mechanical impeller can pump 280 litres a minute. That’s more than twice what your average car can do.


All the hardware and engineering makes the A45 AMG S the most powerful hatch in series production. It makes 415 hp and 500 lb-ft of torque. In a car which also gives you 30 mpg on the motorway. And then there’s the way the power is transmitted – a dual-clutch transmission and permanent all-wheel-drive. The previous A45 had a Haldex-like system which sent power, if necessary, to the rear wheels. This one has a limited-slip differential in the front and electronically controlled clutches in the back. The A45 can send 100% power to either rear wheel, and it shows in the corners.


The car will measure your steering input and then do anything, anything, to propel you toward the apex. The outer rear wheel gets so much spin when you turn the wheel that understeer never happens. Turn-in is rapid owing to the front diff and chassis bracing. The smallest AMG is reinforced with extra metal everywhere – cross-beams on the underside, strut brace, supports under the engine, and even at the A-pillars to prevent them from flexing over bumps.


Mercedes-Benz AMG A45 SThere’s even a Drift Mode. You can’t get around the fact that it is an AWD system, so you need a bit of momentum and a lot of heavy-handed steering input to make it spin. The Mercedes A45 AMG is a lot of car for your money, but it is astronomically expensive for a supermini. Expect prices to start from a little over £50,000 and will undoubtedly rise considerably when you start adding on some options such as the adaptive dampers. But isn’t the baby AMG more special than its price tag?


We look forward to getting our hands on one to test properly and confirming if we agree with Harris’ claims, or whether we think he may have just been venting at influencers more generally!


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Nick Fox

Automotive Videographer, Photographer and general Car Enthusiast.