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Engine options, top speed, acceleration and refinement

At the introduction of a turbocharged motor, the way power is delivered is as important as the raw figures.

There is no drama with the latter; the M4 is a ridiculously fast car, with launch control ensuring that it passed 60mph from rest, in our hands, in 4.1sec, and 100mph in 8.8sec.

I can't help but wonder what the BMW's engine might sound like without the augmentation

Despite a claimed 155mph limited top speed, it took only 25.2sec to hit 160mph on MIRA’s mile straight, passing a standing quarter mile in 12.3sec and at 120.9mph on the way. That’s only a fraction slower – a single tenth over a quarter mile – than a 2012 Porsche 911 GT3 RS.

Power delivery is a different question entirely. BMW has fitted two relatively small turbos – each working on three cylinders – to ensure they spool up quickly.

The engine is canted to clear the bonnet and has a sophisticated oil return system to avoid starvation and thus cope with the track-day running that is so essential to enjoying this car’s capabilities.

In practice, the turbos may be small, but they do have an effect. No matter how minimal the lag is, there’s no question that this is a less responsive engine than a naturally aspirated one and therefore comes with less urgency to a throttle prod than any M3 to date.

That fact appears harsh when written down, because on the road, for the most part, it doesn’t matter. Yes, there is the tiniest delay between asking for a lot and getting it, but BMW has still crafted an engine that is better than any of its turbocharged peers. It is silky smooth, revs commendably high and, at higher revs, responds as closely to natural aspiration as it’s reasonable to expect.

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There’s also the argument – and it’s not a bad one – that to obtain the same performance at a given road speed, you’d have to have a naturally aspirated engine in a lower gear and wound much further around its rev range to prove as devastatingly effective as the M4.

In fourth gear, for example, an M4 will go from 30-70mph in 5.4sec. The last generation Audi RS5 won’t quite manage that even in third (it wants 7.6sec in fourth). A Mercedes-AMG C 63 will match that in third but takes 9.1sec to cover the same benchmark in fourth. Put simply, an M4 gives away a degree of response but, in return, is faster through more of the rev range.

It also sounds good. Engine noise is amplified through the speakers, and all the more so if you select the powertrain’s settings that give you more revs if the gearbox is in D and more noise when you’re on the gas. We tended to leave the powertrain in its sportiest setting and change gear ourselves.

The brakes of our test M4 were the optional carbon-ceramics. Feel and response were good, even from cold – carbon-ceramics have come a long way in that respect – and they showed no sign of letting up after repeated laps of our handling circuit.

On track, they responded better to a gentler initial application of the pedal, which eased weight transfer to the front, than they did to a sharp stab, which more quickly set the ABS alive, resulting in a stopping distance that was no shorter.