It’s hard to imagine, that the Mercedes-AMG S63 Coupe could be so thoroughly improved with a mid-cycle update. After all, we rated the big coupe as one of the finest cars we’d ever driven. Sure, it might have lacked the last few degrees of sophistication, jaw-dropping engine stats and all-out range-toppingness of the frankly ludicrous, V12-engined S65, but you never felt short changed when driving the S63 Coupe.

But the new car is a major step forward and it’s all down to a change of engine. Because gone is the old S63’s 5.5-litre twin-turbo V8 and in slots Mercedes’ latest 4.0-litre unit. Now, in principle this is closely related to the motor that powers the new S560 Coupe and Cabriolet, but while the lumps in the front of those cars come out of Sindelfingen, the S63’s powerplant is pure Affalterbach.

The M177 is an engine we already know and appreciate, of course, from the AMG GT, C63 and, latterly, the E63. So versatile is this twin-turbocharged V8, that its peak power figure runs a 100kW-spread from 350kW (C63) through to 450kW (E63 S and S63 models, including the Coupe)

Mercedes-AMG S63

With 450kW and 900Nm, fed through a nine-speed automatic transmission, the S63 can reach 100km/h in a claimed 4.2 seconds and go on to a top speed of 300km/h, assuming you opt for the AMG Driver’s Package that lifts the limit from 250km/h (and likely standard in Australia when cars arrive in the first half of this year).

If there’s a real gain it comes in efficiency – which may not, let’s face it, be the primary concern of the car’s customer base. But CO2 emissions plummet from 237g/km to just 203g/km, and you may even see the right side of 12L/100km in daily use, given the new official combined consumption of 8.9L/100km.

Get the new S63 on the road, though, and it soon becomes clear that the transformation is about more than just hard data. Cruise along at motorway speeds and the engine fades away beneath wind and tyre noise, delivering a refined experience that’s not a million miles away from that of the regular S560.

Flick the Dynamic Select switch into Sport or Sport+, however, and the engine reveals impressive duality. Even from the depths of the grand piano-sized engine bay, it manages to deliver one of the best V8 engine notes on sale today – accompanied, of course, by plenty of crackle from the AMG sports exhaust as you bleed off the throttle.

And you will find yourself lifting off often. There’s no sledgehammer effect to your kidneys – the delivery is too linear and the mass simply too great for that – but the V8’s spread of torque (that 900Nm is produced between 2750 and 4000rpm) and the snappy shifts from the Speedshift MCT gearbox are more than enough to deliver a suitably rapid progression from slow to fast. Fast enough for corners to arrive pretty quickly.

Mercedes-AMG S63

You should never be under the illusion that the S63 is a sports car, of course. But it is surprisingly happy to be hustled. There’s a solid front end here, coupled with well-weighted and accurate steering, so you soon learn that you can carry a considerable amount of speed into corners. The body stays admirably flat, too; in fact, this five metre-long coupe only really gets grumpy when you ask it for a sequence of extremely rapid changes of direction. There is, we must admit, one caveat in this appraisal: the car we drove was a 4Matic+ all-wheel-drive example on pretty smooth Californian asphalt, while all S63 Coupes in the UK and Australia will be rear-wheel drive. And the car’s most obvious rival is the all-wheel-drive Bentley Continental GT, which may prove a better all-rounder for British roads and weather conditions, if not those in Australia.

The Merc’s cabin is probably still half a notch behind the Bentley’s, too. Not necessarily in design or technology – because it does get elements such as the S-Class’s dual-widescreen instrumentation set-up and supremely supportive AMG sports seats – but in the finer details, such as the odd switch carried over from lesser Mercs, and the quality of the hide and wood. Viewed in isolation, though, it’s a beautifully finished creation.

And a relatively spacious one, too. If the reason you’re in the market for a car like this is extra practicality over an out and out sports car, you’re unlikely to be disappointed by rear seats that are comfortable enough for grown-ups, at least for a short journey, and a 400-litre boot that’s big enough for a pair of decent-sized suitcases.

In truth, these elements were always among the S-Class Coupe’s more appealing attributes. But thanks to the new engine, this S63 feels like a vehicle whose breadth of talents has just been widened. And to impressive effect. John McIlroy

Specification
Engine V8, 3982cc, twin-turbo
Power 450kW @ 5500-6000rpm
Torque 900Nm @ 2750-4500rpm
0-100km/h 4.2sec (claimed)
Top speed 250km/h (limited)
Weight 1990kg (226kW/tonne)
Basic price c$400,000