BENTLEY will lift the lid on the world's fastest open-top four-seater when the new Continental GT Speed Convertible makes its debut at the Detroit Motor Show later this month.

The promise is one of luxury roof-down touring with the thunderous performance of a 616bhp twin-turbocharged 6.0-litre W12 engine.

We're talking figures of 0-60 in 4.1 seconds, 0-100 in just 9.7 and on to a potential top speed of 202mph - with the added bonus of a 15 per cent improvement in fuel efficiency.

That said, you're still only going to get an average 19mpg and a mere 12.5 in urban conditions.

The four-layer hood, operated at the touch of a button, has been tested in all conditions from -30°C to +50°C or more and is claimed to resist even monsoon-force rain, while there's also a neck warmer.

Sporty touches include exclusive 21-inch alloy wheels, dark-tint grilles, rifled exhaust tail pipes and the winged B badge which crowns the radiator shell is set on a black enamel background.

Inside, exclusive tread-plates scream the word Speed in a cabin that features the handcrafted Mulliner Driving Specification, with its diamond-quilted hide upholstery, as standard.

And Bentley is also offering an exclusive dark tint aluminium ‘engine spin' finish, inspired by the dashboards of the Le Mans winning Bentleys of the 1920s, while other optional finishes include wood veneers and a satin-finish carbon fibre option for fascia and centre console.

The infotainment system includes the brand's latest software upgrades, which include point of interest mapping, optional satellite landscape imagery, live traffic data and digital radio.

Bentley chief Dr Wolfgang Schreiber said: "Following the recent successful introduction of the GT Speed, the new GT Speed Convertible will appeal to drivers who seek the sensory thrills of the world's fastest four-seat soft-top and the practicality of a year-round grand tourer. It is designed for those who accept no compromise."