Andy Enright reports on a BMW that offers searing speed, sleek styling and an engine that has few peers.

If one were to plot a curve that depicted the desirability of a sports car, it often peaks early, trails off gently and then accelerates to rock bottom. Most cars plateau there but a few begin to ascend again. Alfasuds, three-door Sierra Cosworths and Honda NSXs are now starting to look very interesting as indeed is BMW's 6 Series, a car that has emerged from its cheap and cheerful phase and developed into something collectible. The top M635 CSi version (known elsewhere simply as 'M6') long represented the pinnacle of BMW's coupe aspirations. Two decades later, it's back - and how.

The latest version shifts the goalposts to another dimension. It's powered by an engine that features two banks of five cylinders, together developing 507bhp and more than 500Nm of torque. It'll rocket to 60mph in 4.4 seconds and if the electronic limiter didn't call a halt to proceedings at 155mph, the car would comfortably exceed 200mph. Despite this, it's more economical, safer, bigger and cleaner than its predecessor. In real terms it's not even any more expensive. It's hard to escape the realisation that we've never had it so good.

Although the old M6 was often thought of as a less pure sports car than the equivalent M5, this is no longer the case. Whereas the original M6 was, in effect, a 7 Series coupe, the latest £80,755 version takes a contemporary 5 Series chassis and as such offers a stiffer, lighter and more compact body. It doesn't take a genius to figure out that this is one focused performer. The attention to detail reinforces this impression. Like the lightweight M3 CSL, the M6 has a carbon fibre roof. Unlike the M3, its SMG sequential manual gearbox sports no fewer than seven speeds and the enormous brakes will haul it from 62mph to a standstill in just 36 metres, a full 19 metres less than that which the Highway Code deems possible. Around Germany's legendary Nurburgring circuit, the M6 regularly turned in sub eight minute laps during testing, the mark of a true supercar performer.

The M6 looks a degree more muscular than other 6 Series models but the overall effect isn't outrageous. 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 is no ordinary Six, and four exclusive M colours - Indianapolis Red, Sepang Bronze, Interlagos Blue and Silverstone - are offered alongside three other 'regulation' 6 Series hues. Inside, there are fully adjustable M sports seats trimmed in Merino leather and available in Black, Silverstone or Sepang colour schemes. As an option, the hide can also be finished in Portland Natural Brown or, if you're really brave, Indianapolis Red. The dashboard is trimmed in leather and the headlining is Alcantara.

The M6 was never designed to be practical. Nor was it designed to be a future classic; yet this car could end up being just that. Some cars are just destined for greatness and, given the way it makes far more expensive sporting cars appear silly and pointless, BMW's M6 might just be one of them.

FACTS AT A GLANCE

CAR: BMW M6

PRICES: £80,755 - on the road

INSURANCE GROUP: 20

CO2 EMISSIONS: 357g/km

PERFORMANCE: Max Speed 155mph / 0-60mph 4.2s

FUEL CONSUMPTION: 19mpg

STANDARD SAFETY FEATURES: twin front and side airbags, DTC traction control, DSC stability control

WILL IT FIT IN YOUR GARAGE?: 4820/1855/1373mm