When we first sampled the BMW M850i, we were left wondering if there was any need for an M8. Here’s a car that produces 523bhp, will crack 0-62mph in 3.7 seconds, and happily carves up corners like a car weighing quite a bit less. The relative disappointment of the M8 on our first drive didn’t help that mindset, but still, we were left wondering how the two might compare back to back.
Later than planned thanks to you know what, we have the ideal opportunity to find out, using ‘our’ M850i Gran Coupe long-term test car and an M8 in the same body style. And as soon as the two are parked up together, the latter looks like it’s trying to assert dominance over the former.
The M850i is a striking car, with its big face, huge wheels and the sheer amount of space it takes up, but the M8 takes things further with even spanglier rims and all manner of carbon addendum. Inside, there’s less to separate the two. It’s the M8 I jump in first since I’m already versed in the ways of the M850i, and aside from a few trinkets, it’s the much same in there.
The engine seems very similar on paper, too - it’s a 4.4-litre, twin-turbo V8, sharing the same bore, stroke and compression ratio in the M8. There’s a huge list of small but crucial changes, though, from bigger compressor wheels in the turbochargers to redesigned oil passages. And most importantly of all, while torque is unchanged at 553lb ft, it’s significantly more powerful, punting out 616bhp in ‘Competition’ guise.
Interestingly, despite the GC version of the M850i being a couple of tenths slower to 62mph relative to its two-door sibling, the M8 GC hits the benchmark in exactly the same time as the M8 Coupe - 3.2 seconds. Sure enough, the uplift in performance compared to the M850i is immediately obvious, but the difference isn’t night and day; we’re talking about a stupidly fast car and one that’s slightly brisker.
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The noise is much more of a contrast. While the M850i belts out a traditional, burbling V8 soundtrack, the M8’s unusual exhaust manifold - which evens out the gas pulses - has a purposeful flat-plane vibe to it. From the outside, it’s not dissimilar to a McLaren turbo V8.
Impressively, despite extracting a lot more power from a similar-sized engine, there’s no noticeable increase in turbo lag. Thanks to the noise, the later peak power mark (6000rpm instead of 5500rpm) and a slightly higher rev limit (7200rpm, up from 7000rpm), the M8 tends to inspire the driver to explore its upper reaches a little more. The only trouble is, this shows up the limitations of the eight-speed torque converter gearbox.
It’s not a bad transmission by any means, but it lacks the immediacy of the dual-clutch ‘box BMW used to fit in its M V8s, particularly when you’re going for those last-gasp cog swaps. There are different settings to fiddle around with - something you don’t get in the M850i - but that just seems like an unnecessary complication.
Chuck the M8 around the corner, and the different handling attitudes of the two cars soon become clear. The front end is only slightly sharper, but at the rear, there’s a lot more playfulness going on, especially if you’re set to ‘4WD Sport’. You can ditch power to the front axle entirely, but even without doing so, the M8 is far keener to power oversteer than the M850i.
Again, though, we’re not talking about a chasm between these two cars, and it’s not until you’re really pressing on that the distinction between them is obvious. On calmer spirited drives, the experience is disarmingly similar, except for one element - the ride.
Whatever mode you’re in, the M8 is conspicuously firmer. On the road, the damping never seems to settle. The Sport suspension setting can be useable on the right road, while Sport+ is too damn jittery to be used anywhere in the UK away from a smooth race track. Even in Comfort, the M8 can feel too bouncy and nervous, and for little gain in composure.
Switching back to the M850i - the ride in which is far from class-leading - is like floating on a cloud in comparison. There’s less road noise from the wheel and tyre combination here too. As a car to rack up some miles in, it’s far more convincing.
But here’s the thing: I’ve left the M8 behind near the shoot location with a friendly chap who’s loading it into the back of a lorry to be returned to BMW. And the way home isn’t some long dual carriageway cruising session, it’s a reasonably demanding squiggle of road. If the more relaxed attitude of the M850i can leave me yearning for the sharper M8, the latter car will have justified its existence a little more than it has thus far.
That’s not how it pans out, though. Dig deep into the M850i’s abilities, and it can still be outrageously fun to drive. It arguably sounds better, it still feels spectacularly quick, and although it’s not quite so feisty, the rear-wheel steering system - something the M8 doesn’t have - ensures it feels far more agile than a two-tonne fatty has any right too, if not entirely hiding the car’s mass.
Our drive of the M8 coupe revealed a car that was in something of a no-man’s land; not comfortable enough to be a grand tourer, not quite sharp or light enough to be considered a sports car. Driving the GC in the UK and together with the M850i merely highlights this issue.
That’s not to say the M Performance machine is problem-free. Although it has a duality its one-track-mind M Division big bro can’t emulate, the Porsche Panamera is better still at this balancing act. And make no mistake - even if you go for an M850i, we’re talking about Panamera money - it’s £98,758, here optioned up to an eye-watering £118k.
But at least that’s less silly than the circa-£142,000 this M8 GC is specced to. Both of these BMWs struggle to justify their hefty price tags, but it’s the M850i I’m inclined to forgive for this.
It’s far from perfect, it needs to be far swankier inside, and a Panamera GTS walks all over it. But it’s thoroughly likeable, and there aren’t many (perhaps any) BMWs that can claim to be superior to their M equivalent.