In some ways, the CS is the M4 we’ve been waiting for, but in others, it’s extremely frustrating. Those frustrations relate to its day-to-day usability. Those skinny door cards – which are made out of compacted natural fibres – for instance, offer no storage whatsoever and do without speakers entirely. They do incorporate a little armrest, but it’s at such a sharp angle that your elbow always wants to drop off it. There’s no central armrest, either. All minor points, but between them they simply mean the CS is less convenient in everyday use than the much-cheaper standard car.
Otherwise, it’s mostly very good news indeed. The CS's interior is excellent, with high-quality materials throughout, although the suede-trimmed steering wheel is simply too fat and the heavily bolstered seats are woefully short of lumbar support.
The adaptive dampers have been retuned for the CS to make the most of those grippy Cup 2 tyres. The chassis is only a little stiffer than the standard car’s, but it feels so much more immediate and responsive. Within a hundred metres of driving, you’re aware of how much tauter the chassis is and how much sharper the steering feels. On a smooth road, the CS is completely brilliant.
On bumpier, narrower back roads the chassis is just about on the right side of too stiff. Any firmer and the car would skip around hopelessly, tyres losing contact with the road surface at every bump or ridge. As it is, though, the CS has just enough damping quality to deal with a scruffy road and keep its tyres pressed firmly into the asphalt.
The biggest improvement over the standard M4, however, is body control. Early M4s, in particular, felt wayward and loosely controlled at the rear axle, which, combined with a shortage of traction, made them spiky and nerve-wracking to drive. BMW has improved that with each subsequent model year update, but the CS does have the most cohesive and tied-together chassis of any M4 to date. Or any BMW M car for a very long time, for that matter.
On its Cup 2 tyres, the CS finds enormous cornering grip. There’s no understeer in the chassis whatsoever on the road, while traction is now very strong indeed. Of course, those tyres will be well out of their comfort zone even on a damp road, but BMW does offer a less aggressive tyre option.
Through second, third and fourth gears, the CS feels rampantly accelerative. Its twin-turbocharged engine isn’t the most tuneful motor but there’s no doubting the performance it delivers, while throttle response is decent for a turbo engine, if not quite exceptional. The DCT twin-clutch automatic gearbox, meanwhile, feels sharp and snappy in manual mode, but the latest such gearboxes from Audi and Porsche are more responsive still. Sadly, there is no manual gearbox option for the CS.