BMW 6 Series ConvertibleThe new BMW 6 Series Convertible will head up a range of three new 6 Series models, with a conventional coupe arriving later this year and a ‘four-door coupe’ variant due in 2012.

Until the – as yet unconfirmed, but almost certain – M models arrive, this 650i represents the top model in the line-up.

BMW 6 Series Convertible gallery:

BMW 6 Series Convertible gallery

Two turbos, eight cylinders, eight gears

Power comes from a twin-turbo 4.4-litre V8 engine producing 407bhp. It allows the big open-topped 6 to reach 62mph in 5.0 seconds on the way to its 155mph electronically limited top speed.

This drives the rear wheels via an eight-speed automatic transmission, which can be left entirely to its own devices or driven manually via wheel-mounted paddle-shifters.

Opening the 650i Convertible up to the sun couldn’t be easier, with a simple push of the transmission tunnel-mounted switch dropping the top in just 19 seconds.

Open and close on the move

It’s possible to open and close the fabric roof on the move too, so long as you’re doing no more than 25mph.

That might prove difficult, as the 650i is deceptively rapid. Push the accelerator to the floor and it surges forwards with real intensity, and there’s little let up in the force as the speed increases.

The gearbox shifts almost imperceptibly, and the engine is relatively muted until it reaches high revs. For easy speed the 650i impresses, and it’s equally adept at maintaining it on more difficult roads.

Choose how it drives

Optional Adaptive Drive adds electronically controlled dampers and roll stabilisation to the already impressive Dynamic Drive Control system. With it the 6 Series can be set up how you like it: a simple push of a button allows you to choose from a variety of sporting, or comfort settings.

Even on its tautest, most focused set-up the 650i rides with surprising suppleness. With a shell that’s around 50 percent stiffer than its predecessor’s the suspension can work more effectively, blending control and comfort nicely.

The stiffer body also exhibits very little of the shake that some convertibles suffer, to the benefit of refinement and comfort with the roof up or down.

While technically very impressive, the 650i doesn’t deliver the same must-drive character of rivals from Porsche and Jaguar. It’s capable, but it feels a bit remote and uninvolving. Key to this is the steering, which on the launch cars featured BMW’s Integral Active Steer. While it’s precise enough there’s very little feel, which is crucial to an enjoyable driving experience.

There’s more space inside than its predecessor though, with the rear seats offering useable legroom for short trips. It’s certainly a more practical proposition than a Porsche 911 Cabriolet or Jaguar XK Convertible if you need to use those rear pews, though the Mercedes-Benz E-Class Cabriolet is a more spacious all-rounder.

The boot is large in the BMW too, with a useful 300 litres of space on offer with the roof down – and an additional 50 litres available when it’s up. BMW offers a ski-hatch for carrying longer loads.

Practicalities matter little in this class though, with buyers accepting compromises for style. Here the 6 Series delivers, with the exterior styling having some fine detailing and the interior now befitting of a car with a price tag of just under £74,000. And that’s before you hit the options list.

Auto Trader owners are big fans of the previous BMW 6 Series Convertible, giving it a combined rating of 4.6 out of 5 in owner reviews and commenting on its blend of performance and practicality.

Plentiful standard equipment, though expensive to run

Standard equipment levels are high, with 19-inch alloy wheels, electrically adjusted and heated leather seats and dual-zone climate control, though running costs on this particular model will also be high.

With an average fuel consumption figure of just 26.4mpg and CO2 emissions of 249g/km, the 6 Series won’t be a cheap car to run. There will be choices for those wanting a better value 6 Series though, with the twin-turbo six-cylinder 640i improving on those figures markedly.

That 640i manages 35.8mpg and 185g/km, and takes only 0.7 seconds longer to reach 62mph. However, it’s the promise of diesel power and smaller petrol engines that will really see the 6 Series shine – whether the roof’s up or down.

Key facts:

Model tested: BMW 650i Convertible 2dr Auto
On the road price: £73, 430
Date tested: January 2011
Road Tester: Kyle Fortune