BMW XM prototype review: 634bhp hybrid mega-SUV driven

Gulp. They’re building it then?

Yep, here comes the production version of a BMW that promises to fuse the high-riding world of ‘X’ SUVs with the high-speed M Division like never before. The XM is the most powerful BMW ever made. It’s also new from the 22-inch wheels up, which means it’s only the second bespoke M car in M’s 50 year history, after the mid-engined M1 supercar. And M’s first PHEV. 

What’s the new powertrain?

Up front, it’s familiar territory for BMW: there’s a 4.4-litre bi-turbo V8. Not the one out of the current M5 or M8 though: this one’s all new, and tuned to work in harmony with a gearbox-dwelling electric motor. Combined outputs top 634bhp and 590lb ft mean that even at well over two tonnes (no official figures yet) the XM’s going to be up there with the Urus, Bentayga Speed and DBX707 as one of the nuttiest super SUVs roaming the roads. 

Any interesting numbers I should make a note of?

Very little is official yet – the final design isn’t even public (though don’t expect much of a change from the, um, polarising XM Concept). The electric-only range is about 80km (50 miles or so), which is plenty for knocking about in town. And you’ll want to, because this is the first M car with rear-wheel steering. Like the new Range Rover, this huge battle bus is relatively easy to thread through a built-up area. 

Is it fast when I’m out of the city?

The XM saunters along on electric power with its Hans Zimmer-tuned soundtrack humming futuristically. You never think ‘oh, I’m in an iX’ because the ride is really quite taut, even in the Comfort mode. We’d prefer bigger gaps between this setting and the Sport and Sport Plus modes. 

But then the V8 cackles into life. A big V8 does the likes of the M5 or M8 just fine all on its own. But here, with e-boost noticeably filling in the turbo lag gaps, it’s mighty. The XM is absolutely as fast as a super-duper luxury sports SUV ought to be. Which, in case anyone’s asking, is ‘way too fast.’ Meanwhile, the noise is a bit less synthetically dubbed than other V8 BMWs. The exhaust pops are a bit OTT, mind you. 

What has the XM been benchmarked against?

Allow me to introduce my co-driver at this point. Of course BMW doesn’t just lend out its priceless prototypes to Top Gear without bolting an expert into the passenger seat. So, joining us for this test drive is Jens Leopoldsberger (good name) who’s in charge of the XM’s chassis. No mean feat. 

Previously, Jens headed up the chassis department at Rolls-Royce, and signed off the current Phantom and Cullinan SUV. But he says he had a ‘calling’ to come back to BMW and do something schportier…

Anyway, benchmarks. Jens says that the team has been out on the road in a Bentayga, Urus, and (weirdly) a Mercedes G-Wagen, which is a high point for silliness but hardly the most sophisticated handling SUV known to mankind. The internal targets for the XM were to make this larger, more luxurious, hybrid-saddled car handle with the freakishly sharp reflexes of an X5 M. 

To that end, all of the suspension has come from the X5 M, though for extra precision the bushes are niched from the M5. It’s all been treated to new software and calibration for duty in the XM. 

So what’s been the biggest challenge in setting up the XM?

Getting all the systems to talk to each other. The V8, the gearbox, the electrical drive, plus all the modes you can play with in an M car and save to your preference, like throttle response and gearshift speed. Add into that the re-gen system (two levels of recuperation for that) which has to work with the variable Comfort / Sport brake pedal feel. 

And it’s all fed to the road by a minimum of 21-inch rims. 23s are also optional. Jens says the 22s we’re rolling on are ‘the sweet spot’. How did we arrive in a world where 22s are anything other than obscene? German car designers have a lot to answer for. 

And that’s before we’ve had a look at the finished production-spec bodywork. Expect all of the concept’s attitude. Inside it’s new X7 meets current M3. A round steering wheel instead of the iX’s squircle (Jens is most pleased by that), none of the carbon bucket seats (too hard to climb up into) and the latest version of iDrive in a 14.9-inch screen that now features heater controls. No buttons for that any more. Sigh. 

What else did you spot?

On the outside, there’s only one charging point, because the bi-turbo V8 is so tightly packaged that BMW couldn’t squeeze in two sockets. So you’ll need to park this monster creatively to get the cable to reach.

In the back, legroom is almost comically vast. The Chinese market will be most pleased. BMW calls the back seats the ‘M lounge’, which is of course vomit-worthy. But in its defence, the deeply plush wraparound rear seat (a la Rolls-Royce) is fabulously comfortable, and you get a better view out than in an X6. 

The boot’s huge too, but it needs to be, because there’s no hidden cubbyhole for the charging cable. As a result, all XMs come as standard with a black and gold Louis Vuitton-style leather bag with waterproof insides for storing the damp and dog poo-covered wire.

I am not making this up. Buy an XM and you get a single item of posh luggage thrown in on the house. What a world we live in. 

You haven’t mentioned how it drives that much?

Seems odd to when it’s not fully finished. The powertrains occasionally became confused and argued with one another, meaning the XM didn’t smooth out the petrol-electric transition very cleverly. BMW knows about it, and it’s working on tidying that up. The brakes are sorted though: impressively consistent and reassuring. They’re steels, not ceramics. 

How’s the handling?

Pretty astonishing, frankly. 48-volt anti-roll bars keep the high-riding body freakishly flat as the XM is hurled from corner to corner. It’s so good, you wonder if they couldn’t get away with softening the ride off a tad more in a straight line, to keep up the comfort end of the XM’s bargain. 

The engineers say the internal hashtag for the XM project (again, not kidding) is #noundersteer. They want this beast to feel rear-driven, not to wash wide in a bend and kill your confidence. All I can say is if you’ve carried enough speed into a curve on a dry road to get the XM’s nose to push, you’ve got less self-preservation than me. It’s just as keen to prove it’s a serious super-saloon as the X6, which offsets its sheer vulgarity by being annoyingly good to drive. 

When will BMW finish the XM?

Not in time for M Division to blow out the candles on its birthday cake: the 50th birthday is later this month. Finished XMs will be shown off in the autumn of this year, and begin heaving themselves off BMW’s Spartanburg factory floor in South Carolina, USA from March next year.

Why isn't M’s 50th celebration car a supercar?

I guess you could argue super-SUVs are the new supercars. For me, they’re equally as pointless, but the market has spoken, particularly in the USA and China. BMW is a business, M needs to go where the money is, and that’s no longer in lightweight naturally-aspirated rear-wheel drive coupes. 

Ironically, the classic M1 was a bit of a commercial flop for BMW. The M Division’s second go-it-alone car is categorically not going to be.