Fans of open-top two-seat Mercs now have even more choice. These are the first official photos of the Mercedes-Benz SLR McLaren Roadster (to give it its full name), the much-anticipated cabrio sibling of the coupe that came out in 2004.The new McMerc joins straight at the top of Mercedes’ roadster tree, above the SLK and SL. Unlike its smaller cousins, however, the SLR uses a fabric roof, not a folding metal one.The roof – made from what Merc cryptically calls a ‘newly developed material’ – will be available in three colours, and is semi-automatic. It requires the user to unlatch it, after which it folds away electrically in under 10 seconds.Uniquely for a fabric-roofed supercar, the SLR Roadster promises the same 206mph to speed as the coupe. Mercedes also claims that the car’s trick aerodynamics mean you can easily have a conversation with the roof down at over 125mph.As with the coupe, the SLR Roadster is built around a carbonfibre tub, which means it will be extremely rigid, despite the lack of a solid roof. The only metal body components are two aluminium subframes for the engine.The engine is unchanged from that in the coupe: a 5.4-litre supercharged V8 producing 617bhp and 575lb ft. As in the coupe, the gearbox is a five-speed automatic. The Roadster will hit 62mph from standstill in 3.8sec, and features standard ceramic brakes to ensure it stops just as well.Prices have yet to be announced, but we’d expect them to start at around £350,000 when the Roadster goes on sale in September.