The BMW M3 CS is an £86k, 174mph M3

We’ve had the BMW M4 CS and now, with some inevitability, it’s the M3 CS. Wonderful inevitability, though. There’s always something cooler about a sports saloon with four doors rather than two. Unless that’s just us.

Anyhow, all that’s great and good about the M4 CS applies here. So there’s carbon to save weight over standard M3s – chiefly on the roof and bonnet, to lower the centre of gravity – and there’s more power and a snarlier exhaust system. Mind, the M4 CS's slightly pointless (but still geekily cool) fabric door pulls have gone.

Its twin-turbo 3.0-litre straight-six engine produces 454bhp and 442lb ft, figures up 10bhp and 36lb ft on an M3 with the Competition Pack fitted. Which means 0-62mph in 3.9secs and a 174mph top speed, figures which match the M4 CS and improve upon the M3 Competition Pack by 0.3sec and 19mph.

While there are sops to weight saving, its 1,585kg isn't down much over a Competition, as it’s not really a stripped-out special. You can only have BMW’s seven-speed twin-clutch paddleshift gearbox, while adaptive suspension with Comfort, Sport and Sport+ modes is also standard. You get full climate control and a posh Harman Kardon stereo, too. Options include carbon-ceramic brakes and all the Alcantara you can imagine inside.

Want to spot one? It gets a set of wheels inspired by BMW’s DTM touring car, measuring 19in at the front and 20in at the back. They’re wrapped in serious Michelin Pilot Sport Cup 2 tyres. Our experience suggests they’re mega in the dry, but might make the CS a bit bum-puckering in the wet. BMW will let you spec friendlier rubber if you wish.

There’s also a reasonably subtle body kit, much of the extra bits in carbon or carbon-reinforced plastic. Spec it in a sensible colour and (bonnet hump aside) it could almost look like most other M Sport-trimmed 3 Series, but those nerdy enough (like us) will still spot one a mile off.

Just 100 will come to the UK, with orders being taken at the start of 2018. Which gives you a small amount of time to save up the £86,630 it costs before options. That’s a whopping £25k more than an M3 Competition for little more power, but its rarity and badge kudos should ensure they’re all snapped up pretty quickly. Tempted?