On paper, you can draw a lot of parallels with these cars. They’re both rear-wheel drive coupes. They put out around the same amount of power. In terms of the 0-62mph dash there’s only a tenth in it (4.5sec for the M2 and 4.6sec for the Cayman), and the prices are even pretty similar too.
However, that’s where the similarities end, as while they’re both trying to answer the same question, they arrive at two vastly different conclusions. The Porsche 718 Cayman S is a purpose-built sports car with a mid-mounted flat-four, while that BMW is a jumped up version of a front-engined coupe you can spec with a 1.5-litre engine should you wish.
Take a closer look, and the whole purpose built sports car deal with the 718 is even more apparent. It sits all squat and low, and it’s one of those cars you fall in, rather than get in. Is the interior an exciting space? I’d have to say no, but - just like that optimally mounted engine - everything’s in the right place, and there’s something nicely purposeful about that 918 Spyder-inspired steering wheel and its rotary drive select switch.
Having spent a lot of time with the 718 Cayman’s soft-top cousin earlier this year - the 718 Boxster - I’m keen to get started with the Porsche before the BMW. A twist of that half cool/half lame car-shaped key later, and the boxer engine behind me clatters to life with a vocal yet not terribly melodic growl.
Ah yes, that engine - now infamously packing four cylinders rather than six, and thus causing rage in many dark corners of the internet. But you know what? I rather like it. The old 3.4-litre made a spine-tingling noise, but it never really felt that fast. Fairly linear the power delivery of this 2.5-litre, 345bhp engine may be for a turbo engine, but it’s strong in the mid range, and while peak power comes at 6500rpm, there’s little penalty (about a five per cent drop in power) in buzzing it all the way around to the 7500rpm rev limiter.
Do that, and the gruff, Subaru Impreza-like growl at the low end is a distant memory, replaced with an effervescent zing that rings through the cabin just before you slot in a new gear on the slick and mechanical-feeling six-speed manual gearbox. Given all the moaning about this Cayman and its Boxster stablemate apparently not sounding good enough, the great irony is that this new engine probably makes a better noise than any four-cylinder engine fitted to a current car.
Do you get much in the way of efficiency benefits in return for the displacement drop and change in noise? That’s a debate for another time, but while it’s worth pointing out that the 718 will push 40mpg on a motorway cruise, it certainly drinks like the old six when you’re pressing on: today we’re hovering around the 15-16mpg mark. But I don’t want to get caught up in that now, I just want to revel in how deliriously good this chassis is.
We already know the Boxster is a brilliant car to chuck about, but add a tin roof and the associated increase in rigidity, and you get a package that’s even more focused. The old car was undeniably the best sports car you could buy for the money, but this one’s stiffer, grippier and a hell of a lot faster. It’s a masterclass in sports car building.
The BMW’s up next, and after sliding into the oh-so comfy helm, a prod of the starter button results in a throttle blip from an engine that’s unmistakably packing an extra pair of cylinders in comparison to the Cayman. It’s far from the best straight-six I’ve ever heard, though - the hopped-up, 364bhp N55 turbocharged 3.0-litre lump puts out a distinctive, throaty exhaust note much like the M3/M4, supplemented by the very unwelcome warble of BMW’s Active Sound Design feature pumped through the speakers.
It’s a strong engine though, with a much meatier-feeling low-end than the Cayman, thanks in part to 33lb ft more torque on offer. There’s also less rear-end grip here, and the M2’s fat torque delivery means the traction control light flickering away like a broken Christmas tree light becomes a particularly familiar sight. I quite like that.
Reaching some corners, and the difference between the Cayman and the M2 is plain to see. The M2 can’t change direction as quickly, rolls more in the middle of the corner, and doesn’t grip as tenaciously. The gear change isn’t as slick, either.
However, all of that is about as surprising as an explosion in a Michael Bay movie. Sure, the M2 has a track that’s 58mm wider at the front and 45mm wider at the back compared to an M235i, plus bits of M4 in its suspension and an electronically controlled M limited-slip differential, but it’s still not a sports car built from the ground up like the Cayman is. And that shows.
But, what’s perhaps surprising is that it isn’t all that far away. What’s more, with less rear end grip - not to mention a totally manageable attitude when it does let go - it’s the more fun, playful car. And that’s before you factor in the raspy six-pot engine note belting out of the quad tailpipes. Yes, it’s not the most amazing-sounding six, but the M2 is still the better sounding car here.
Then we have cost to consider. While the Cayman is a little nicer inside, at £48,834 it’s getting on for £5000 more than the better equipped, £44,080 M2.
So it’s a slam-dunk win for BMW, right? Not necessarily. Yes, it’s the more entertaining, much less expensive BMW that wins my heart, but you simply can’t ignore just how good the Cayman’s chassis is. There’s nothing like it this side of a supercar - well, other than a Cayman GT4 - and other than going without rear seats, the Cayman doesn’t give away as much as you’d think in the practicality stakes. Seriously, it still has a capacious boot at the rear plus a sizeable frunk big enough to swallow an Alex Kersten, giving more luggage space than the M2 overall. Bet you weren’t expecting that, were you?
So which should you crave the most? It all comes down to what you want from a sports car: do you want to be astonished, or do you want to be entertained? I reckon there’s a strong case for either.