Review of the new BMW M6 Convertible

On August 19th 1960, Captain Joseph Kittinger strapped himself to a hot air balloon as part of the US Air Force's Project Excelsior. He rode the balloon twenty miles straight up, staying at peak altitude for 12 minutes as he waited for the balloon to drift over the landing target area. Checking his equipment carefully, he then stepped into space. Despite the use of a small stabiliser chute, Kittinger accelerated to supersonic speeds until at an altitude of 17,500 feet, he deployed his main chute and landed safely in the New Mexico desert. The whole descent took 13 minutes and 45 seconds. You and I may not be able to replicate Captain Joe's achievement but dropping the roof and accelerating BMW's M6 Convertible to its top speed would give almost as big a rush.

When the electronic speed limiter intervenes, you would be covering ground at 227 feet per second at an altitude of around 36 inches. A thin pane of glass is all that separates you from stonechips, small birds and insects transformed into lethal projectiles. The 155mph maximum velocity is the peak wind speed of Hurricane Katrina, enough to reduce a city to anarchy and blow houses, cars and livestock into the next zip code. Fully 507 horsepower is straining against the leash to propel you still faster, up towards three miles a minute. Balloons? That's kids stuff.

At first it's not easy to square the image of BMW's svelte 6 Series Convertible with the sheer fury that is the M6 coupe. Meld the two cars together and you have an odd beast, something that can flip between personalities capriciously. This M6 drop top certainly looks a good deal more muscular than other 6 Series Convertibles which can, from certain angles, look a little awkward. A deeper front valance houses air intakes for the engine and brakes, plus there are swooping sill finishers and a rear valance that incorporates a diffuser. The four telltale rear exhaust pipes are the big giveaway that this car is bringing some serious heat. BMW offer a competition package for the M6 convertible that enhances driving dynamics through revised suspension configuration. The package also features a contoured bonnet and double-spoke light alloy wheels with wider rims.

"It's not easy to make a logical case for the M6 Convertible but it's simple to come up with a whole lot of appealingly illogical ones"

Rather oddly, the roof was a big talking point of the M6 Coupe, finished in carbon fibre as it was, but with this model you get a conventional fabric affair capable of disappearing from view in less than 20 seconds. The best part about the hood is that it's operable with the car moving at speeds of up to 20mph. Much quicker than that and aerodynamics would plant your hood onto the windscreen of the car behind but it's nevertheless very impressive to be able to drop the hood while on the move. Six hydraulic cylinders guide the ragtop into place without significantly compromising luggage space - a major issue with folding hard topped cars.

The Convertible retains the coupe model's near 50:50 weight distribution and the car's contours are preserved with C-pillar style fins. Many soft-top cars look a million dollars with the roof down but around a hundred with the soft top in place. The 6 Series also features a retractable glass windows and noise insulating polyurethane foam sandwiched between the rubberised outer membrane and the inner hood fabric.

The designers have done their best to minimise wind noise and a quick trip through a car wash will show that water ingress just isn't worth worrying about. The shape of the car directs airflow away from the passenger compartment and at speeds of over 100mph, front passengers will encounter very little in the way of turbulence. With the roof in place, the boot offers a generous 350 litres of space and 300 when it's folded. Manufacturers love to measure capacity in terms of golf bags (target market) and this boot is capable of carrying two.

The M6's Mdrive Manager allows the driver to pre-select specific settings for the Power button, SMG gearbox, stability control system, electronic damper control. As seen on Chevrolet's Corvette, the M5 also features a Head-up Display projected onto the lower section of the windscreen. The default setting shows vehicle speed and a rev counter, the data flashing at the driver when the next gear needs to be selected.

Power is transmitted to the rear wheels via the world's first production seven-speed sequential gearbox. The Drivelogic system changes gears around 20 per cent faster than the somewhat unsatisfying earlier iteration of the SMG gearbox as fitted to the M3. Eleven different change patterns are offered, six of which allow the drive to alter the speed and response characteristics of the gearchange in manual mode and five that govern the rules of the automatic mode. The sixth pattern in manual is reserved for the Launch Control function, giving the likes of you and I the opportunity to replicate BMW test drivers' 0-60 times. In theory at least.

A revised DSC stability control system has also been developed specifically for the M6. This features three settings, the default mode offering the full safety net of electronic features. An M Dynamic mode allows the enthusiast driver to let it hang out a little, the system allowing a little sideslip and opposite lockery. For the genuine hooligan and determined tyre fryer, a third press of the button disables the system completely although if it takes a very skilled and committed driver to wilfully break the traction of the monster 285/35ZR19 rear rubber and hold it there.

A drop top M6 may sound a dilution of the M brand values but when the result looks as good as this and allows you to get closer to some frankly apocalyptic performance, any complaints seem churlish.