Geneva show: McLaren 650S raises the roof

McLAREN has finally pulled the covers off its 650S Coupe and Spider convertible, with the latter losing almost nothing in acceleration ferocity or structural integrity despite the decapitation.

Based on the four-year-old MP4-12C mid-engined supercar – but with 25 per cent new parts including a P1-flagship inspired nosecone – the new ‘Mac’ has wowed Geneva show-goers with its stunning looks, 3.0-second sprint time to 100km/h, 329km/h V-max and fresh Tarocco Orange hue.

Only the 8.6s 0-200km/h rating – a 0.2s discrepancy in favour of the coupe – betrays the 1370kg Spider’s 40kg weight penalty.

On the flipside, the drop-top’s electric two-piece roof system that is responsible for virtually all of those additional kilos can be retracted or re-erected in under 17 seconds and at speeds of up to 30km/h.

Significantly, McLaren says the 12C-based carbon-fibre MonoCell chassis required no additional reinforcement since it provides all of the 650S’s torsional strength regardless of configuration.

This means that the removal of the roof has no consequence in terms of strength or rigidity.

“Most competitors do not offer high-performance iterations as convertibles due to the compromises that invariably plague open-roof cars,” McLaren said.

“These models will be heavier and have substantially less torsional rigidity, to the detriment of handling and ride.”When in convertible mode, the roof can be stored underneath a body-coloured tonneau cover incorporated as part of the 650S’s twin rear buttresses.

Otherwise that area doubles up as additional luggage space.

Other Spider details include a heated glass rear window. Operating independently of the roof, it acts as a wind deflector in open-top mode, cutting turbulence, while it can be lowered to allow more engine noise inside the cabin should the occupants need to hear the 650S engine in full flight.

As seen in the coupe, the engine in question is a heavily revised version of the 12C’s M838T 3.8-litre twin-turbocharged V8, delivering an identical 478kW of power at a heady 7250rpm and 678Nm of torque at 6000rpm.

Likewise power is transmitted to the rear wheels via a seven-speed dual-clutch gearbox known as the SSG.

Remarkably, despite the 40kg weight gain, the Spider matches the coupe in averaging 11.7 litres per 100km on the European combined fuel economy cycle, for a carbon dioxide emissions rating of 275 grams per kilometre.

Both models come standard with carbon ceramic brakes, ‘650’ lightweight alloys shod with 235/35 R19 tyres up front and 305/30 R20 rubber out back, satellite navigation, Bluetooth telephone and audio streaming with voice control, digital radio and an Alcantara-trimmed cabin.

As with all the McLaren cars, the 650S is manufactured at its tech centre in Woking, Surrey, England.