To share, or not to share? Part one

The first part of the answer is, of course, that BMW did not need to design a lighter car. Dan himself says the car was ‘a joy to spend six months with’. He also reports that the 454bhp punch of that sublime 3-litre straight-six S58 engine and the sophistication of the chassis tuning means that the BMW disguises its mass very well indeed – modern chassis engineers have proved their ability to make even the porkiest of tall SUVs float like butterflies and sting like bees, so it’s not that surprising that BMW’s chassis team could make a relatively compact sedan feel agile, 90 per cent of the time.

Nor will I linger long on the cynical but oft-proven observation that, sadly, most of the sports car buying public don’t give a fig about mass. If they did, your local Cars & Coffee would be jammed with Lotuses and Alpines, and the guy turning up in the 911 would get all the attention, as enthusiasts pointed out this unusual German rear-engined car from the boutique Stuttgart brand.

So let’s try to figure out the real reason the M2 is such a boat-anchor. Well, the clue is in the title of this piece, I guess. For the G87 M2 sits on BMW’s could-have-gone-through-the-naming-committee-one-more-time CLAR or CLuster ARchitecture platform. This is BMW’s take on the ‘modular’ platform, a recipe that almost every large OEM has cooked up in the last couple of decades. Rather than having a single ‘skateboard’, for want of a better word, OEMs design modular architectural blocks – front end, rear end, centre/floor sections and technical modules like powertrains, HVAC systems, high-voltage batteries, not to mention the all-important and eye-wateringly expensive electrical/electronic architectures – that are sufficiently technically compatible to (more or less) plug together without needing the huge investments that a whole new platform would require.

Imagine a giant Lego Technics set, but with each block costing hundreds of millions of euros. CLAR was BMW’s take on this industrial playbook, comparable to VAG’s PPE/PPC, Renault’s CMF or Stellantis’ STLA platform families, to take just one forkful of other OEMs’ alphabet-spaghetti of similar approaches.

Platform sharing is, of course, not a new thing. You could argue that its origins date right back to when car companies only bothered building platforms – you would buy a naked rolling chassis from Bentley in the 1920s and take it to your favourite coachbuilder (Mulliner, Vanden Plas or James Young to name a few) to have it clothed in coachwork of your choice. Right through the history of the car, canny car makers have sought to spread the costs of expensive underpinnings while making the bits of the car we see (and hence buy) as different as possible.

The heyday of platform sharing (arguably) was the 1990s, when increasing technical complexity of platforms, largely driven by more sophisticated emissions and crash standards, started to make them really expensive to develop, even for the deepest of OEM pockets. Finance departments crunched some hard maths and realised that there was money to be made in making multiple upper bodies or ‘Top Hats’ on shared platforms. Renault was one example of an OEM that went all-in on platform sharing. The bustle-bummed second-generation Mégane was just one of five Top Hats sitting on the same X84 platform. The strategy was successful enough for Renault to generate enough of a treasure chest in the late 1990s to buy almost half of Nissan, all of Samsung Motors and still have enough francs left over to snap up Dacia.

So by the time BMW launched CLAR in 2015, the platform sharing playbook was a well-thumbed one. The lead programme – the first car sitting on a new platform – was the G11 7 Series. And that lead vehicle is really important. No matter how the engineers try to project themselves mentally into the second, third, fourth or tenth vehicle planned for the platform, that first car, the one that drives the practical engineering decisions, always leaves its DNA indelibly on all the others.

And I think this is where we find the technical answer – or at least, a heavy hint – as to why Dan’s sky-blue fighter had to constantly suck in its tummy. Because the CLAR platform covers a bewildering range of vehicles indeed – from 3, 5 and 7 Series sedans, through a whole mess of SUVs from X3s, X5s, X6s, X7s and Ms, and taking in a few oddities like the Z4/Toyota Supra double-act on the way.

The CLAR platform also has to house a pretty impressive range of engines – from modest three-pots all the way up to the big V12s, turning just the rear, or all four wheels through a range of manual and auto gearboxes.

Now, the ‘old’ M2 sat on a stretched version of the platform designed for the 1 Series. It was hence the bigger, more powerful car sitting on a ‘small’ platform. The second-gen car is the opposite case – it’s one of the smallest cars sitting on a sled that was really designed for larger, heavier cars. Its front side-members will probably be a bit stouter than they need to be in order to handle the crash loads of its bigger, more luxurious brethren. Those side-members’ span will be a bit wider than really needed to house the M2’s straight-six – because they also have to swallow the V engines used elsewhere. The lower A-pillar structure – a crucial node in any car’s structure, where lots of crash and front suspension loads come together – will again be a bit stronger than strictly needed. The floor centre tunnel and sills will all be, let’s put it politely, ‘over-engineered’.

The added mass will not just impact the body structures coming out of the BMW press shop. Bought-in suspension members, steering systems, braking parts – all will be a bit beefier than really needed.

So, should we pity the latest M2 for all this penalising mass, and assume the poor engineers hated every minute of the job? As enthusiasts, should we cry in our coffee over our fate of forever being stymied by those killjoy accountants?

Not for a minute. Because platform sharing is the sharpest of double-edged swords. Yes, the M2’s weight is a good example of the downside – that’s why we’re picking on it as a case study here. But let’s look at the upside. The upside is that the M2 exists.

That BMW judged it to be financially viable in 2023 to build such a specialised, squarely performance-orientated car for the enthusiast market is quite remarkable – and would simply not have been possible without all those other cars sitting on the CLAR platform, picking up the tab for the M2’s lunch.

Yes, in an ideal world all engineers would find themselves in the position I once (and only once) did – designing really focussed, featherweight sports cars on absolutely bespoke platforms, not intended to be shared with any other models. And yes, in those circumstances mass can indeed be pared down to the absolute just-so-and-not-an-ounce-more limit. But it’s exceedingly hard to break even at that game, never mind making the profits that shareholders in a company like BMW demand.

More realistically from a business point of view, it is much better to take a platform that can be shared with more prosaic models, and effectively use the volume punter’s money to pay for our hobby. And that’s what BMW has done with the M2. Okay, it’s easy to be picky and say it’s a bit of a porker. But I’m still damn glad that it exists. If the price of having cars like this on the road is a bit of dirty-fingernail platform sharing, and a car that lightweight purists get a bit sniffy about, it’s a price we should be glad to pay.

Before we sign off; in the myriad list of cars sitting on the CLAR platform, one interesting one snuck in there in 2018 – the iX3, an all-electric version of the X3. And this car opens a whole second dimension to platform sharing – a relatively recent one. That is, should OEMs try to design platforms that can also accept EV powertrains? Are the compromises imposed by containing the batteries just too great, or is a broad church, one-size-fits-all approach the smart play? And who the hell invited hybrids to get into the bed as well?

That’s a bit too much to get our heads around for today, so we’ll pick that up soon in part two.