Parkers overall rating: 4.1 out of 5 4.1
  • Four engines, three petrol and one diesel
  • Huge performance from all
  • Eight-speed auto as standard

There’s a choice of four engines in the BMW 8 Series Convertible, three petrol and one diesel, and all offer huge acceleration and supreme driveability.

Petrol engines

The petrol range starts with the 840i and its 3.0-litre six-cylinder engine. There’s 340hp on offer and it has a 0-62mph time of 5.3 seconds. This is also the only 8 Series Convertible that’s solely rear-wheel drive.

Next up, the mid-range M850i xDrive is powered by a 530hp V8 with 750Nm and has a 0-62mph time of 3.9 seconds.

That 4.4-litre powerplant can channel its noise straight into your ears thanks to the open roof, meaning more aural drama than the potent-but-distant soundtrack of the Coupe.

BMW 8 Series Convertible engine

An increase in weight of approximately 125kg compared to the coupe means the 0-62mph time dips by two tenths, but make no mistake, the 8 Series Convertible is still suitably fast.

It’s satisfyingly drivable at all speeds, with plenty of low-down torque allowing you to gather pace smoothly in a higher gear than normal, rather than pinning everyone to their seats with a screaming engine at high revs. It’s a hugely versatile engine that suits the 8 Series Convertible’s character down to the ground, allowing you to bumble along and be lazy one minute, or be spirited the next.

If you need a sudden turn of speed however, you’ll still find a delay between putting your foot down and having to wait for the eight-speed automatic transmission to deliver its power onto the road, adding to the sensation of the extra weight on board.

This also isn’t helped by the engine’s turbocharged power delivery, which can feel blunt in that it delivers all its performance in one big lump with little reward for revving the engine out to its limit. This also goes for the exhaust; it’s certainly loud enough at low revs with plenty of crackles, but it sounds a bit monotone and doesn’t get any better higher up in the rev range.

BMW M8 brings upgraded V8 engine

The BMW M8 Competition uses an upgraded engine of the one found in the M850i. It’s powered using a developed version of the 4.4-litre V8 but in an even sportier guise – codenamed S63, rather than N63.

This means you get upgraded cooling and oil systems, as well as a high-pressure injection system. The result is a power upgrade to 625hp, although the torque figure of 750Nm remains the same. The 0-62mph time drops down to 3.4 seconds and top speed remains the same at 155mph - although the M Driver’s Package brings this up to 190mph.

Just like the M5 saloon, you have the option to send power from all four wheels solely to the rear, changing the character of the vehicle dramatically.

The M8 Competition comes with an even quicker-shifting double-clutch automatic gearbox for maximum performance. It’s a joy to use during spirited driving when using the steering wheel-mounted paddles and is particularly smooth, even if the rev limiter cuts power abruptly, like with the M850i. The toggle switch on the gearlever (below) also allows you to change the ferocity of the gearchanges, with a suitable Comfort setting to offer a more relaxed driving experience.

BMW M8 Competition Convertible automatic gearbox 2019

Diesel engines

The BMW 840d xDrive features a 3.0-litre straight-six diesel with 320hp, peak torque of 700Nm, and a 0-62mph of 5.2 seconds.

BMW expects this engine to sell just as well as the petrol, thanks to its reasonable economy and powerful performance.

Handling

  • Bold promise of luxury and engagement
  • Delivers pretty well on both counts
  • Lots of tech to help shrug off weight

The BMW 8 Series Convertible promises a tricky combo of driver enjoyment and the ability to transport up to four occupants in luxury – two characteristics we’d normally consider mutually exclusive.

However, it largely delivers on both counts, albeit with a firm emphasis on up to four passengers, and the need to deploy the might of BMW’s active chassis tech to help mask the size and weight of the 8 Series.

Raft of tech on offer

Unless you select the entry-level 840i, which doesn’t come with any of these, all models of the 8 Series Convertible come with xDrive all-wheel-drive to help improve traction, adaptive M suspension to smooth out the roughest of roads, and Integral Active Steering, which pivots the rear wheels to make the car feel smaller around town and more stable when pushing on.

If you pick the petrol M850i you also get an M Sport differential thrown in, which divides power to the rear wheels more accurately and in doing so brings better grip and agility especially on corner exits.

Other model specific or optional equipment includes active roll stabilisation to neutralise body roll and larger, more effective brakes denoted by lairy blue callipers.

BMW 8 Series Convertible driving

What is the BMW 8 Series Convertible like to drive?

Well, compared to the Coupe there has been a fair bit of shoring up to do to make up for the lost torsional rigidity provided by the roof.

The 8 Series Convertible is built around an already stiff Carbon Core, but losing the roof inevitably means more weight, particularly in the rear, which does blunt the car’s performance and edge somewhat.

That said, the Convertible feels suitably stiff as a result, with no stereotypical wobbliness in corners or on lumpy tarmac, so it’s a fair trade. The steering is light and the brakes are strong, so it’s very easy to drive around towns and cities.

The BMW is still sharper than a Mercedes-Benz S-Class Cabriolet, but it’s fair to say all the tech required to counteract its size and weight is situated between you and the actual process of driving, making it feel less engaging than a smaller sports car.

M8 Competition allows you to choose between four- and rear-wheel drive

The sharp steering on the M8 Competition is responsive and helps this large convertible feel incredibly easy to pilot. It’s hardly surprising to say that it doesn’t feel as alert as the coupe, but the rear-wheel steering system helps tighten up the line as you apply more lock. 

Thankfully, there isn’t too much artificial weighting applied in the sportier drive modes that blight other BMWs, and it’s easy to build a rhythm down an entertaining stretch of road – even if it’s at a dialled-down pace compared with the coupe. 

Fundamentally, it’s still sharper to drive than the more luxurious Bentley Continental GT and Mercedes-Benz S-Class Coupe. The handling is still composed enough when set in its most docile Economy and Comfort modes, and while that’s not necessarily what certain luxury buyers want, die-hard BMW fans will appreciate the extra body control.

Handling characteristics heavily dependent on drive mode

In normal driving conditions, the M8 Competition doesn’t feel like an obvious leap up from the M850i in terms of driving experience. It requires you to cycle through the drive modes into the more aggressive settings to notice the difference.

There are a multitude of these to choose from in the BMW M8 Competition, giving owners a high level of configuration to reach their desired setting. You’ll need to spend some time as an owner to try each sub-parameter and find your preferred balance, otherwise you can simply cycle through Eco, Comfort, Sport, Sport Plus and Track to automatically adjust throttle sharpness, steering weight, suspension firmness and the loudness of the exhaust for you. 

Driving in Sport mode is best avoided as the M8 Competition doesn't really feel comfortable at all in this state, with all the controls being dialled down as though they’re being held back with restraint, accompanied by an engine that sounds like it’s being strangled.

BMW M8 Competition Convertible drive modes 2019

It’s fine for bumbling around towns and cities in, but the rest of the car doesn’t particularly feel comfortable in this state of tune when being driven in a sporting manner. You’d be better off switching into Sport Plus for the engine and chassis to feel more alert. 

There are three settings for the drivetrain as well. The default all-wheel drive mode actively shuffles the power from the front wheels to the back efficiently, while Sport AWD ups the level of fun to be had, delivering a slightly rear-biased all-wheel drive system. This setting is a good middle ground, as you can have some fun here within the grounds of safety.

The rear-wheel drive setting is not recommended for use on public roads, and while that may be deemed useless for most, this is where you’ll find the biggest transformation in the car’s character over the M850i.

You can also select between two levels of brake pedal pressure, to make it feel more positive under spirited driving conditions, but this doesn’t make any actual different to the maximum amount of stopping power available.