Although some claim sleeper cars are a dying breed, I’m not sure I agree. Take the F90 BMW M5 - yes, it has swollen wheel arches and a quad exhaust, but for the most part, it’s not significantly more outlandish than an M Sport-kitted 5-series. Keep it in a subtle colour, and most won’t realise you’re in a 592bhp super saloon sledgehammer.
The M5 you see here, however? It’s an M5 CS, and it’s not so discreet. It’s been specced in the same way as the car used in the original press pack photos, which means ‘Frozen Deep Green’ matte metallic paint and a gold finish for various bits including the new 20-inch forged wheels and the stainless steel exhaust tips. However optioned, the M5 hampers its Q-car thing with a massive power bulge in the middle of the bonnet. It serves no practical purpose, so I want to hate it, but it’s one of my favourite things about the CS. Damn.
The vents which flank it are actually functional, at least. And on the inside, the special CS touches continue. There are CS-specific carbon-backed leather seats with big holes in them, which are great if you like the idea of being poked in the back by your six-year-old sitting behind. Speaking of which, the rear seats get some hefty, hip-hugging bolsters that remind me of my old (perpetually broken) Mercedes 190E 2.3-16. This does hamper practicality somewhat since the rear bench now only seats two, and can no longer fold down.
The printing of the Nurburgring Nordschleife layout on the headrests is cringeworthy but well-executed and offset by far nicer additions like an Alcantara steering wheel with a perforated 12 o’clock marker. The finishing touch is a big CS badge on the dashboard, in case you forget what you’re driving. Although I’m not keen on all the tweaks in here, it does feel special and distinct from ‘lesser’ M5s.
The most important changes aren’t as obvious to the naked eye. As a kick-off, that new bonnet plus the boot and diffuser are made from carbon fibre reinforced plastic. Normally optional carbon ceramic brakes are fitted as standard, meanwhile, giving a total weight saving of 70kg. With 626bhp on offer, the CS is 10bhp pokier than an M5 Competition, and it sits 7mm lower on stiffer springs. Finally, those gold 20s are shod in Pirelli P Zero Corsas.
It’s hard not to get overwhelmed by the sheer straight-line ability of the CS. The car’s ability to gain speed with manic vigour dominates the experience, making me wonder if that official power figure is a little conservative. BMW says it’ll do 0-62mph in three seconds dead, three tenths faster than a Comp, but I suspect it wouldn’t be hard to improve on that.
The 4.4-litre twin-turbo V8 provides a hammer-blow of power and torque with only a little dash of lag. The eight-speed automatic gearbox effectively shuffling cogs, if not with quite the immediacy and aggression of a dual-clutch transmission. The other thing missing? A truly stirring soundtrack. As with every other F90 M5 we’ve tried, you get a surprisingly polite, at times almost flat-plane like noise from this thing. It’s all down to the manifold, which evens out the exhaust pulses. Cars like the M550i don’t have this, which is why they sound rumblier.
Exactly how the M5 behaves in corners depends on the settings, of which there are many to pick from. On the first drive, the level of complication is irritating, but for an owner, it’s not so much of an issue - it doesn’t take long to work out your preferred setups and save them to the steering wheel-mounted M1 and M2 switches. For me, this is Sport Plus for the engine, the third and most aggressive setting for the gearbox, comfort for the steering and suspension and MDM for the traction control. The latter also engages the ‘4WD Sport’ mode. See what I mean? Complicated.
Set thusly, the M5 has a playful side that previously took a back seat in the more neutral ‘4WD’ mode. The changes for the CS, especially those Corsa tyres, bring more life to the steering, and more bite to the front end. The way you can throw the CS about constantly surprises - even with 70kg lopped off, this car is just 100kg shy of the two-tonne mark.
This doesn’t seem possible considering the way the CS happily dances around through a tricky set of corners, although it only gets away with this up to a point. Up the speed by a few miles per hour, and you’ll quickly be reminded of the M5’s bulk, despite the stiffer springs doing a better job of propping the car up. Keep within this car’s optimum operating window, though, and it’s sublime.
A side effect of those suspension changes is a noticeably firmer ride. This is just about bearable, primarily because the CS usually settles down nicely after negotiating imperfections in the road surface. There also isn’t a huge amount of bandwidth in the adaptive dampers, so it’s possible to switch to Sport or even Sport Plus suspension on the road without the car feeling brutally harsh.
Impressive though this car is, it leaves us with a similar conclusion to the M2 CS. The tweaks are noticeable but not fundamental to the way the M5 drives. They don’t make the CS a ‘must have’ over the Competition. Plus, one of those with the Ultimate pack of options is £20,000 less. Yes, you’re looking at an M5 that costs £140,000.
As was the case with that extra-special M2, the M5 CS is more of an advert for just how good the Comp is out of the box. If you choose to spend the extra, the CS does just about enough to justify the premium - it’s just that doing so isn’t strictly necessary. Should we be pleased BMW has given the option, though? Most certainly.