Engine options, top speed, acceleration and refinement

And so to that kerb weight. This may be the most powerful road car that BMW’s M division has made but, in as-tested form, it weighed precisely the same as the original F90 BMW M5 that we tested in 2018 (1940kg on the scales, fully fuelled). It also develops the same 553lb ft of torque as the standard M5 did (albeit over a broader band of revs). Could it be that much quicker against the clock?

Believe it. Whereas the standard car needed 3.3sec to hit 60mph from rest and 7.5sec to hit 100mph three years ago, the CS cuts the former to just 3.0sec and the latter to a faintly staggering 6.8sec. Our test car did that on Michelin Pilot Sport 4S tyres, it’s worth noting. On a warm set of the standard-fit Pirelli Corsas, there’s reason to believe it could go a tenth or two quicker over both measurements.

M5 CS is more supple and composed in its body movements than the regular M5 manages and it is remarkably agile and immediate in its responses for a car of its bulk.

Whichever tyre it’s on, then, this is a near-two-tonne, four-seat executive car that’s as quick as a supercar up to the national speed limit. It goes through a standing quarter mile at precisely the same prevailing speed as a Porsche Taycan Turbo S and would be travelling significantly quicker than the Porsche by the time a standing kilometre came up. It isn’t in every sense the very biggest-performing four-door on the planet, because there are a handful of rivals – both electric and piston-powered – with slightly greater firepower. But it misses that mark by a margin so small that you might well consider it completely insignificant and you’d be very unlikely to notice it on the road.

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The M5 CS is nothing short of breathtaking in full stride. BMW’s updates to the engine manifest themselves in better mid-range throttle response than any current-shape M5 has had hitherto; an even freer power delivery right at the top of the 7200rpm rev range; and a noticeably more authentic-sounding, enticing audible character. Torque is produced in less of an elastic-feeling surge and in more accurate doses defined by the precise position of your right foot. And it keeps coming well beyond 6000rpm in a way that you still don’t find in too many turbocharged performance engines.

The accompanying V8 soundtrack is that little bit more raw than in even an M5 Competition, BMW having not only fitted that new stainless steel active exhaust but also removed sound insulation from all around the car, and also fitted a carbonfibre bonnet that evidently lets a bit more V8 noise out into the wild. You can hear more induction hiss when you first apply power, and then more turbine combustion howl as the revs rise, with matching audible drama coming from the bellowing exhausts behind you. Between them, those influences balance out BMW’s digital engine noise synthesis much more effectively here than in any other current M5, and they make for a markedly more likeable and genuine performance character for the car.