BMW has revealed a more potent and track-focused version of the M4 as the latest entrant into its motorsport-inspired CS lineage.
Following on from the existing ‘Competition Sport’ versions of the M2, M3 and M5, the new M4 CS has more power, less weight and a reworked chassis set-up compared with the Competition car, in a bid to improve its straight-line performance and on-limit handling.
It packs the upgraded version of the M4’s twin-turbo 3.0-litre straight six that featured in the limited-run CSL, upping its peak power from 523bhp to 543bhp with an increase in turbo boost pressure from 1.7 bar to 2.1 bar.
Although the CS does not produce any more torque than the Competition, it sustains its 479lb ft peak for an additional 220rpm at the top end of the rev range, holding it from 2750rpm to 5950rpm.
The powertrain has also been reworked in order to endure long sessions on the track: the engine’s cooling system is improved, for example, and the supply of oil to the clutch has been increased to ensure the four-wheel drive system maintains its performance.
Stiffer engine mounts, which are bespoke to the CS, are also said to improve the powertrain’s responsiveness.
In addition to extra power and flexibility, the CS is also 20kg lighter, courtesy of a titanium exhaust silencer and various carbonfibre-reinforced plastic (CFRP) components, including the centre console, gearbox paddles and various interior trim pieces.
With less weight and extra performance from the engine, the CS cuts the 0-62mph sprint time from 3.5sec in the Competition coupé to 3.4sec, while its 50-75mph time is quoted at 2.6sec in fourth gear and 3.3sec in fifth.
The CS’s chassis has been tuned to improve steering precision and wheel control, with stiffer springs and anti-roll bars that are also said to reduce roll through tight bends.
The stability control system has also been reprogrammed to raise the limit at which it intervenes to correct a slide.
The extra slip afforded by this higher limit helps the CS to put more power down to the road when driven with what BMW describes as “an extremely sporty driving style”.
The BMW CS borrows its staggered lightweight wheels from the previous M3 CS, with 19in alloys up front and 20s at the rear.
These are shod in Michelin Pilot Sport Cup 2 rubber as standard, but the more track-focused Cup 2 R compound is also available as a no-cost option.
The product of all the changes is a Nürburgring Nordschleife lap time of 7min 21.99sec, nearly 6.8sec quicker than the BMW M3 CS and just 3.9sec behind the more hardcore BMW M4 CSL.
As well as improved performance, the M4 CS is distinguished by distinctive yellow-tinted daytime-running lights, in a reference to BMW’s GT race cars.
The grille is outlined in red, as with the M3 CS, and a couple of the saloon’s paint finishes – Riviera Blue and Frozen Isle of Man Green – are also carried over to the coupé version.
Prices for the M4 CS start from £117,100 (RRP). Order books will open at the end of the month, ahead of deliveries starting this autumn.
