THE designers who penned the new BMW 6-Series Convertible say they got their inspiration from the movement of waves caused by the bow of a powerful motor boat.

Well, surely wasn't that just marketing speak from BMW as the Bavarian-based marque introduced their latest soft-top masterpiece which is available just in time for what we all hope will be a long, hot summer.

But looking carefully at the long, low-slung, wedge-shaped machine, it doesn't take long to see where they those boffins are coming from.

For no matter what angle you view the car from, and from what position along its length, those beautifully-sculptured lines and creases flow and sweep along every panel, while even the waistline surface which leads the body into the interior, can be said to "mimic the look of a boat deck".

And keeping with the nautical theme, each side of the low folding roof ends with projecting fins merging gracefully on to the rear panel in front of the boot lid.

The 6-Series Convertible comes with two turbocharged petrol engines, the 640i with its three-litre, straight six-cylinder 320hp power house, and the 650i driven by a truly-awesome 407bhp 4.4-litre twin-turbo V8. Both are mated to an eight-speed automatic gearbox.

With so much power available, both models have been electronically limited to a top speed of 155mph.

Standing to 62mph takes just five seconds for the larger engined car and 5.7 seconds for the 640i. Fuel consumption is 26.4 and 35.8mpg respectively, while CO2 emissions are 249 and 185g/km.

Hitting the road from Gibraltar into the hills above Spain's Costa del Sol in the powerful 650i proved a fair test for this dream machine.

The tight, hairpin-loaded highway is just what this car has been built for, stable and grippy through the bends themselves while offering masses of grunt when given a touch of welly along the short straights that linked what was basically an endless series of S-bends.

The fabulous throaty rasp from the V8 engine completed what turned out to be a sensational driving experience.

As you might expect with a £73,430 price tag, the 650i is superbly equipped with an abundance of safety features and electronic aids that add to the driving pleasure.

While the chassis is set up for a sporty ride, the car was also fitted with BMW's optional Adaptive Drive system, which allows the driver to select one of four finely-tuned driving modes, from comfort, normal, sport and sport+.

Another unique feature on the car was the optional Integral Active Steering system which adds steering to the rear axle via electric motors.

It allows the rear wheels to turn by up to 2.5 degrees to add extraordinary agility in situations such as those encountered on the twisty mountain passes of our test route and also in busy city traffic.

At up to 37mph the rear wheels turn in the opposite direction to those at the front, reducing the car's turning circle by half a metre, while at higher speed, the rear wheels turn the same way as those on thr front to offer a more composed high-speed ride.

As you would expect in such an expensive piece of kit, the interior is a work of art, with heated leather seats, satellite navigation, brushed aluminium or high-gloss wood trim and the rest of the fittings and fixtures straight out of the top drawer.

Other standard features include cruise control, Xenon lights, Bluetooth, USB connectivity and sport multi-function steering wheel with gearshift paddles, while options include a head up display which projects driver information onto the windscreen, park assist and night vision with pedestrian recognition.

For such a big car, there is not too much legroom in the rear, and while adults would be able to get in with a bit of a push, they would struggle to get comfortable on longer journeys.

However, only 1,000 6-Series Convertibles are due to hit our shores this year, so this is going to be an exclusive experience for those who manage to grab one.