BMW 640d Convertible review

BMW's 6 Series Convertible now features sleeker styling and a more focused agenda. Jonathan Crouch finds out why the super-efficient 640d is the pick of the range.

Ten Second Review

Better looking and cleverer than before, the latest BMW 6 Series Convertible looks a more convincing proposition. The handling's sharper, the infotainment is state of the art and, as before, in 640d diesel guise, you get the kind of performance and economy combination you simply wouldn't expect a luxury convertible of this kind to offer.


For any grand touring convertible to be judged an unqualified success, head-turning ability is mandatory. The latest 6 Series answers that call with some elan. We've had two main versions of this car since the turn of the century and the most recent one has been updated with suspension tweaks, a slightly sharper look and extra multimedia connectivity. This is the car we're going to look at here, the version in question being the one with the diesel engine most customers choose. The 313PS 640d combines real-world 50mpg economy with a sub-6.0 second 0-62mph sprint figure and can comfortably cruise on the autobahn with the wind lightly ruffling your hair at over 120mph. Sounds tempting for lottery winners? Let's check this car out.

Driving Experience

The suspension of this improved 6 Series Convertible has been given the once-over to improve ride quality and reduce noise entering the cabin. Set-ups can also be further personalised through options like Dynamic Damper Control, which varies its responses electronically according to where and how the car is being driven, Adaptive Drive, which includes roll stabilisation, and Integral Active Steering, which introduces an element of rear-wheel steer to reduce the amount of turning effort needed while offering the perception of increased agility. Here, we've been looking at the variant that is by far the biggest UK seller, the 640d diesel. Clearly aimed at customers who want the wind in their hair but keep a cap on consumption and emissions, it gets a 313bhp 3.0-litre twin-turbo straight six engine with variable geometry turbochanging and BMW's ECO PRO system fitted as standard which gives improved economy when driving at low speeds or cruising and is claimed to combine a 0-62mph time of 5.6s and electronically limited 155mph top speed with 50+mpg economy. An eight-speed Sport automatic gearbox is standard, as is Drive Dynamic Control, which allows drivers to choose how responsive they want the gearbox, steering and throttle to be. More technology? How about the optional Integral Active Steering system. This combines Active Steering for the front axle with a steering rear axle, allowing the steering angle and power assistance to be controlled at both the front and the rear with the help of electric motors.

Design and Build

The styling of the Convertible has been nipped and tucked a little, with a re-profiled front bumper with a broader kidney grille, revised headlights featuring an LED main beam, a redesigned rear bumper and different alloy wheels. The six-cylinder models get 17-inch wheels but most owners will upgrade to the eighteens. The cabin has come in for a bit of a makeover as well, with materials quality taking a noticeable boost. The latest model gets some higher-quality dash finishes and optional two-tone leathers. There's still not a huge amount of space in the rear, the back seats best reserved for jackets and bags. The boots not a bad size at 300-litres, although it's still a bag or two down on that of the Mercedes SL.

Market and Model

There are two 640d Convertible variants, the standard SE model and, for a premium of around £2,300, a more dynamic-looking M Sport version. Prices for this 313PS 640d diesel derivative start at just over £68,000, so you're looking at a premium of around £2,700 over the 320PS 640i petrol-powered alternative. BMW has built a good deal more equipment into the car this time round, with the key item of user technology being ConnectedDrive. This provides full navigation and infotainment facilities, and includes a SIM card which gives the driver access to Concierge Services. This can be tailored to the owner's preferences and includes helpful information such as Real Time Traffic Information, BMW Teleservices and Intelligent Emergency Call. It can even reserve hotel rooms and find flight information, ATM machines and out-of-hours pharmacies. Can you imagine the buyer of an original 6 Series back in the Eighties being told a car could do all that? ConnectedDrive is also linked as standard to the latest version of the BMW Head-Up Display, which projects essential safety and guidance information - from speed limits to navigation instructions - onto the windscreen within the driver's field of vision. In certain circumstances, telephone number lists and entertainment information can also be called up. There's the almost obligatory camera and radar tech, in this instance called the 'Driving Assistant Plus' package, incorporating Active Cruise Control with Stop & Go, Lane Departure Warning and Pedestrian and Collision Warning with Braking.

Cost of Ownership

Nobody buys a premium convertible like this 6 Series if they're fanatical about saving pennies, but the 640d more than upholds BMW's reputation for efficiency. While both the 640i and 650i are very economical given the amount of power their respective engines generate, the diesel six of the 640d takes things to another level, returning a fairly amazing 50.4mpg on the combined cycle which equates to just 149g/km of CO2. The automatic transmission features Auto Start-Stop technology and an automatic active air flap control behind the car's kidney grille for optimum engine performance. The convertible also gets Brake Energy Regeneration, Electric Power Steering (EPS), ancillary components that power down when not being used and intelligent lightweight construction. And just think about this for a moment. Go for the 650i and you're looking at 31.0mpg with CO2 emissions of 213g/km.


If you're in the enviable position of not having to worry unduly about the finer detail of your disposable income, the 6 Series Convertible looks well positioned, especially in 640d guise. As for his improved version, well the boost to the interior materials quality and the inclusion of ConnectedDrive as standard are tangible improvements that customers in this category will certainly value. The styling changes aren't going to convince too many floating voters but the 6 Series Convertible remains a class act. Less showy than a Bentley Continental GTC, far fresher than a Mercedes SL and guaranteed to be better screwed together than a Maserati Gran Cabrio, it's hard not to see it continuing BMW's record of success.