The reveamped drivetrain should benefit from a freer-breathing exhaust system similar to the one fitted to the M3 Competition with less sound deadening.
The CS will undergo a weight loss programme compared with the regular M3, with lightweight carbonfibre-reinforced plastic bonnet, carbon rear diffuser and fixed-height front splitter. Inside, there will be thinner door cards and a lighter stereo, which combine to cut around 35kg from the Competition Pack’s 1560kg weight.
The improvements will help trim the M3 CS's 0-62mph sprint time to about 3.9sec – three-tenths better than the M3 Competition. The electronic limiter that restricts the M3 to 155mph will be removed, raising its top speed beyond 170mph.
The M3 CS will sit on an adjusted version of the M3 Competition’s suspension to offer sharper responses, with 10-spoke forged wheels shared with the M4 CS that come wrapped in Michelin Pilot Sport Cup 2 tyres. Optional carbon ceramic brake discs, also shared with the M4 variant, will be offered.
The M3 CS will be priced to sit above the M3 Competition Pack, likely around £85,000. This price would make the CS £23,420 more than the Competition Pack but about £4000 cheaper than the two-door M4 CS. Unlike the M4 CS, which sits below the M4 DTM and M4 GTS models, the M division is not expected to produce a higher-ranking version of the M3.
Although BMW refrained from commenting on the M3 CS when contacted by Autocar, the ‘werkstestwagen’ - ‘factory test car’ in English - decal on the rear of the spotted development car backs information that it is the CS prototype being used by the M division. The performance arm has a base at the Nürburgring, where all of its road and race machines are developed and tested.