AN open top version of the McLaren Artura plug-in hybrid supercar has been announced and it comes with a power upgrade taking its output to 700ps.

Said to be the lightest convertible in its class - beating rivals by as much as 83kg - the Artura Spider has a top speed of 205mph and a 0 to 62mph acceleration time of three seconds.

With an official fuel return of 58.9mpg the car can now run for 21 miles purely on electricity - and the same 20ps power upgrade is also being made available on the coupe model.

The Spider's one-piece roof can be retracted automatically in 11 seconds and McLaren is also offering the car with the option of an electrochromc roof which can either brighten the cabin - or block more than 99 per cent of sunlight - at the touch of a button.

Boot space is a maximum of 160 litres.

The car is priced from £221,500 - some £32,000 more than the coupe - and has a power to weight ratio of 480ps/tonne from its 3.0-litre V6 and E-motor powertrain.

Michael Leiters, McLaren chief executive, said: "The new Artura is absolutely the complete next-generation supercar, whichever model you choose.

"We have upgraded the powertrain and the chassis systems to deliver more power, more dynamic performance and even higher levels of connection with the driver - without any compromise in everyday driving.

"And now alongside the new Artura coupe we have the Artura Spider, a new convertible that has all of these improvements and brings another dimension of open-air McLaren supercar exhilaration to our range."

The car is fitted with an eight-speed automatic transmission and has three driving modes - comfort, sport and track - while a launch control system for optimised performance on track is standard, as is a new ‘spinning wheel pull-away' feature.

Activated by disengaging electronic stability control by pressing the ESC button on the driver binnacle, this allows dramatic wheelspin when accelerating from standstill with a large throttle load.

McLaren says recharging the battery to 80 per cent capacity can be done in 2.5 hours.