interesting, I always thought the gearbox was the worst part of out smart four two. I always found it took a long time to change gear, particularly noticeable when fulling away in traffic, it would keep up with the traffic flow easily until it changed from first to second, but it took longer to change gear that I could have manually changed gear and all this time there is no drive to the wheels, and traffic would get nearer to the back of the smart than was comfortable. Once it was pulling in second it would holds its own and even accelerate faster than the rest of the traffic, then you would get the same thing when changing from second to third, but not as noticeable.
I had the clutch bit point re learned at the merc dealers, this made the change of gear smoother but did nothing for the slow change, dealer said it was 'normal' so I just lived with it
Cheers,