BMW says the 8 Series Convertible is in a class of its own. It’s certainly a BMW like no other…
FARO, PORTUGAL — This is the BMW M850i xDrive Convertible, and it answers a riddle: How do you make a car twice as fun while adding just five percent to its price?
Ok, maybe the math is a bit questionable if you’re not a fan of convertibles but really, slicing the roof off a coupe, as BMW has done with the 8 Series, is an almost sure way to amp up the glamour and sensation of driving a powerful car with two doors.
And given how immersive driving an open-top car with the roof down can be, you know you’re in for a hell of a ride when the roofless machine under you happens to be a brawny M850i xDrive. Here’s what you’re in for…

Very nice! So BMW is doing… a what exactly?
Well, start with an M850i xDrive coupe, and replace the metal roof with a folding cloth top. It slips under a tonneau in 15 seconds at up to 50km/h, with the mechanism optimised for speed (note how the lid pivots up and out of the way) and silence; electric motors do the work, but you never hear them whir.

 

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In turning fierce coupe into glam cabrio, BMW has satisfied two musts. One, the 8 Series looks (even) better as an open top car, thanks largely to the long, low deck that forms the rear without adding the bulk that convertibles sometimes pack on.

Two, with the roof overhead, it still has the profile of a sporty coupe, with the cloth top enclosing the cabin without looking like someone stretched an umbrella over the car.

The coupe’s lines still flow more gracefully, especially in the way the roofline sweeps down to meet the tail, but all in all it’s been a fine conversion.
Here’s a quick look at the coupe for comparison:

Presumably, the usual compromises apply?
Some, but not all. Extra wind noise? Forget it. The top is multi-layered, with a sheet of sound-deadening material inside that seals the cabin from outside din — BMW says the Convertible is actually no noisier inside than the coupe.

Like all cabrios, the 8 Series is heavier than its fixed roof equivalent, in this instance by some 125kg. That’s down to extra metal to reinforce the body and put back some of the rigidity that cutting the roof off subtracts, of course, and the result here is mighty impressive: the Convertible is just 2 percent less stiff than the coupe, so the body never judders and the steering wheel doesn’t quake in your hands when the BMW hits a hump.
Ah, but the boot is smaller, surely?
It is, but don’t call me Shirley. Start with 450 litres of cargo space in the 8 Series coupe, then subtract 100 litres for the Convertible because the roof has to live somewhere when it’s not overhead. Also, there are pyrotechnic pop-up bars to keep you from getting a permanent new hairstyle if the car rolls over. That system takes up space, too.
Still, you can fold the rear seat backs and create a load-through portal for lengthy stuff. Incidentally, that’s why you have a conventional wind deflector now instead of the slide-up window that the 6 Series Convertible had.

And the rear seats?
Er, CarBuyer is ashamed to say that its expert correspondent forgot to actually try them. But it does look tight back there for legroom, while the structural reinforcements for the body take up some room, which means the seating itself is more upright now.

Anyway you’ll never buy an M850i for the rear seating, whatever the roof. Those rear perches are only there in case your wife ever quizzes you about the car and you want to say that it’s a four-seater.
What counts is the driver’s seat.
How so?
Duh, the M850i xDrive Convertible is, well, an M850i xDrive. That means four wheel drive, 530 horsepower and a chassis distantly related to the M8 GTE, a moderately successful racing car.
The Convertible might be a heavy car, breaching the two-tonne mark, but that V8 has serious muscle, and it can hurl the BMW to 100km/h in a Ferrari-like 3.9 seconds. That may be 0.2 seconds slower than the coupe, but with the roof down you feel much more of the speed, and you get the front row experience when it comes to the V8’s tuneful burble.

Choose Sport Plus mode and things firm up without becoming uncomfortable, while the exhaust rumbles and backfires menacingly.
All the M850i’s music is natural, by the way. Other BMWs use electronic sound generators, but there’s no auto-tune here. What you hear is purely produced by petrol.

Does it go around corners?
Heck yes. Rear axle steering is also standard (as is air suspension) and the mixed size Bridgestone tyres were tailor made for the car, so the M850i resists understeer pretty heroically and feels more agile than something its weight should.

If anything, you find yourself braking a wee bit earlier than you can when the hairpins approach. Learn to leave it a bit later and it’s pretty astonishing how quickly the Convertible can fly through every bend, over and over. It’s a car that covers ground both rapidly and tirelessly.

Shouldn’t I get an actual sportscar for that?
Well, if you’re the keenest of keen drivers, then yes. A Porsche 911 would be more satisfying, and a Mercedes-AMG GT, more thrilling. But the BMW is highly versatile, so it offers more pace than the average man would dare to exploit, while slathering a layer of feathery comfort over everything.

The cabin materials are mostly top notch, and if you cruise around with the roof overhead you’ll be in a cosy space physically, and a good place mentally.
Say I want one. When can I have it?
November this year is our best guess, but if not then exactly, then thereabouts. Next year is when things get complicated, however. There’ll be a faster and presumably more rowdy M8 version, and at the other end of the scale, an 840i xDrive (we expect 340 horsepower and 100km/h in 5 seconds) whose lower price should make it the volume seller.
It’s worth saying that open top cars aren’t for everyone, but with the 8 Series BMW seems determined to make sure that there’s one for as many different types of buyer as possible.

BMW M850i xDrive Convertible