BMW M4 AC Schnitzer ACS4

More power, less ride height – is this what the M4 needed?

This is a slammed BMW, the wheelarches now crammed to the limit by new 20in Schnitzer alloys

10 January 2016

One look at this M4 shows you you’re dealing with something different. It’s the way it sits, squat, purposeful, oozing aggression. This is a slammed BMW, the wheelarches, which always looked pretty full, now crammed to the limit by new 20in Schnitzer alloys.

Under the bonnet the original and muscular twin-turbo straight six has seen some serious work done with the ECU. Power is up from 431bhp to 510bhp and torque up from 406lb ft to 475lb ft. Given that the original set-up could frequently provoke a torrent of chittering from the stability control system, it seems faintly daunting that power and torque have gone up by so much.

However the key difference is in that lowered suspension. It would be easy to make the already very firm suspension simply immobile by lowering the ride height but somehow Schnizter have managed the opposite. Its RS suspension kit is a passive springs and damper set-up seems similar to the original at lower speeds, in that it’s still capable of inflicting some pattering along bumpy roads that feels as though there is rather more spring than damper to the fore.

The AC Schnitzer RS suspension gets into its groove as speeds rise

But where the original tends to keep that feeling whatever the speed, the AC Schnitzer RS suspension gets into its groove as speeds rise. As bumps get faster and bigger the suspension seems to respond with much more control, adding firm but controlled damping to the springing movement. Where the hard M4 can get chucked about on bad surfaces at speed, this version seems more to glide over them. Power and control.

And there is a lot of power. To be honest, on wet, secondary English roads at the beginning of winter, there’s simply too much power to fully explore the envelope, even with the uprated suspension. Oh for a sunny day and a dry road, but that will have to wait for another time.

BMW M4 AC Schnitzer ACS4 has a lot of power

So for now we have an upgrade which does definitely add something to a standard and ferocious M4. The interesting thing is that if you wanted to keep the original steel brakes, which work really well, and didn’t go for the ceramic upgrades, you’d save about £6,250. And that’s not far off what the engine and suspension upgrades from Schnitzer would cost – which would be a much more worthwhile investment. Just the suspension kit would make most owners very happy indeed, and better able to explore the full potential of their M4.

BMW M4 AC SCHNITZER ACS4

Engine: 2,979cc 6-cyl twin-turbo

Transmission: 6-speed manual/7-speed dual-clutch auto (M DCT), rear-wheel drive

Power (hp): 510@6,800rpm

Torque (lb ft): 475@4,000rpm

0-62mph: 4.0sec

Top speed: 155mph (limited)

Weight: 1,612kg M DCT (EU, with driver)

MPG: 34 M DCT (NEDC combined)

CO2: 194g/km M DCT

Price: £80,871 inc. VAT