Live launch: Bentley Continental SS convertible

Just arrived in Denver in the US in preparation for the Bentley SuperSports Convertible launch. Quite a long way from the UK for Bentley to launch a car, but the weather is probably necessary to premiere Bentley's fastest, most hardcore drop top. I mean it: this is a rug-top that hits 202mph and gets to 62mph in just 4.1 seconds - even though the Convertible droops the scales at a not-inconsiderable 2395kg. That 621bhp motor is pretty epic though: 590lb ft, biturbo, 6.0-litre. Bentley reckon that the Convertible will do just under 17mpg on the combined cycle. Any guesses to what might be achievable on test in the mountains?