The ForSpeed also does without a roof, so you'll need to hope that it doesn't rain. There is a weather cover, but it's only for unused seating positions. Should it rain whilst you're driving, rest assured that the interior has been waterproofed and there are drainage channels in the seats.
With a name like ForSpeed, this Smart has a lot to prove. The company claims that it can go from zero to 60km/h in 5.5 seconds. No zero to 100km/h time is quoted, presumably because top speed is just 120km/h.