Mercedes’ new A45 AMG S is no ordinary hot hatch

That is, of course, entirely expected. Mercedes has been tantalising us with the prospect of its new compact super-sports model for ages. The semi-skimmed AMG A35 hinted at what was coming, then more recently there was confirmation of what would be under the bonnet of the full-fat AMG A45 – an engine that raises the bar again for what a mere 2.0-litre four-cylinder engine can produce.

The new A45 was always likely to be the car enthusiasts would wait for. Mercedes has pushed the envelope of hot hatch performance ever since it first let AMG loose on its A-Class, and the new one was hardly going to get any less powerful. This is going to be a near £50k car after all (price not yet confirmed), with the likes of the almost-as-powerful Audi RS3 and BMW M2 in its sights.

So, has the wait been worth it? The power we already knew – 420PS (415bhp) in the S, 40bhp up on the outgoing model and, on specific output, more efficient than many exotic combustion-engined supercars.

But what we didn’t know before is just how much else has changed about this new version. AMG has clearly made an effort to make it fun as well as fast.

First, though, the figures, and, on paper at least, not all that different from before. 0-62mph for the S version comes down from 4.1 to 3.9 seconds. With standard Race-Start (launch) function, milli-second-shifting eight-speed twin-clutch gearbox, 245/35 R19 rubber and smart all-wheel-drive, how much quicker off the line could a five-door car perfectly capable of taking the family on a day out be?

It’s a bit unfair to compare old with new but it’s still telling to remember that 30 years ago a Lamborghini Countach needed around 5.0 seconds for the same 0-62 sprint…

As before, top speed is electronically limited but to 168mph (270km/h) in the S version rather than the 155mph of before. Opt for the Driver’s Package and you can get the same higher top speed in the base A45, a car with “just” 382bhp and barely slower 0-62 time of 4.0 seconds.

They are the figures, what about the fun? How has Mercedes-AMG “raised vehicle dynamics to a level previously unimaginable in the compact class” as it claims to have done?

Interest centres on a new rear differential featuring two electronically-controlled multidisc clutches, one for each rear wheel, which allow torque distribution to be varied between the left and right sides, as well as between front and rear axles. This allows for a range of dynamic possibilities linked to the multifarious drive mode options, including a new Drift mode, standard on the S model, for powersliding antics on a track.

The promise is that a lot more besides has changed over the first A45. Any of the larger, stiffer, better riding models in the new A-Class family hints at what lies in store, but this ultimate version takes things to a higher level again with a thorough reworking. Reinforcing struts under the car and between the front suspension towers result in the stiffest A-Class structure yet, for what Merc says is more agile handling, less body roll and pitch than before and also a better ride.

The suspension components and electro-mechanical power steering have been tweaked, and the brakes made bigger: the S gets six-piston fixed callipers up front and 360 x 36mm discs. Incidentally, the red-painted callipers with black AMG lettering are the way you tell an S version, along with larger, fluted exhaust tailpipes.

The new AMG A45 also promises sharpened responses thanks to further development of the eight-speed AMG Speedshift transmission and, most of all, to the new engine. A new twin-scroll turbocharger, with roller bearings for the first time, improves engine response, while Nanoslide piston linings, as used by the Mercedes F1 cars, are a factor in allowing a broader rev range, now peaking at 7,200rpm. There’s more torque than before too, with the S model’s 500Nm (369lb ft) peaking at 5,000rpm.

A not-a-lot-of-people-know-that fact about the new A45 is that it is unique among A-Class models in having its engine turned around. It is still transverse, but now rotated so all the intake gubbins is at the front, the turbocharger and exhaust at the back. Mercedes says it helps with cooling and aerodynamics.

What else to expect? More exhaust pops and bangs than ever as the gearbox automatically double-declutches itself down through the gears when in sport mode. Lots of AMG Dynamic Select drive modes. Lots of gloss black surfaces, yellow or red highlights and black artificial leather and microfibre materials in an interior that is already the class of the field. And lots of options, as ever, including having your AMG A45 either in five-door hatch or four-door CLA coupe form.

You can also expect AMG looks: this is the first A-Class to get the panamericana-style wide grille with its 12 vertical louvres, just like all the grown-up AMGs. The shark-like nose, slim lights, powerdomes on the bonnet, flared arches and all the usual AMG aero addenda (some it optional, even on the S) complete the picture.

Good looking? We think so. But in this regard at least, it’s no Lamborghini…

Photography by Joe Harding.