THE biggest clue is in the number, as the name synonymous with Grand Prix glory prepares to launch its fastest ever series-production supercar.

The McLaren 650S is also billed as the brand's most engaging, best equipped and most beautiful model too - and few visitors to next month's Geneva Motor Show are likely to disagree.

It joins the McLaren stable of thoroughbreds alongside the 12C and sold-out McLaren P1, and will be up for grabs as a fixed-head coupe or spider with a retractable folding hard top when it hits the streets this spring.

That 650S badge refers to the power output - 650PS - of the British-built twin turbo V8 engine and the S stands for Sport.

Performance figures will be confirmed ahead of Geneva, but will improve on the 12C's top speed of 207mph and 0-62mph figure of 3.1 seconds.

McLaren says the car's design is inspired by the P1 and has a front bumper that sits below new LED headlamps while a more integrated front splitter helps boost downforce. In fact at 150 mph, downforce levels are increased by 24 per cent.

And unique door blades behind the front wheels direct air from the trailing edges of the front splitter, further benefiting front-end grip and overall balance.

The company has also further developed its Airbrake, which kicks in whenever the car senses extra downforce is advisable as well as its ProActive Chassis Control suspension system which adjusts ride and handling modes for Normal, Sport and Track.

Ride comfort and refinement are said to be to executive saloon standards and the 650S will come with sat-nav, Bluetooth, digital radio, audio streaming and voice control as standard.

Options include fixed-back carbon racing seats, an electric steering column adjustment, rear parking camera and extended carbon fibre throughout the cabin.