My car is still limited to 250 kph (156 mph).
The speedo shows 256 kph, probably due to an accuracy error (Mercedes is well known for a precise 250 kph limit).
Please look at the tach on the right, only 4600 rpm at 250 kph. The engine is set to rev up to 6500 rpm.

Video 1 - Top Speed with a curve at the end (around 2.5 MB)

Video 2 - Acceleration from standstill up to around 240 kph (around 2.5 MB)

Sorry for the bad quality, I took the video one-handed with a tiny Casio Exilim S3 camera.
During acceleration from standstill to 240 kph (2nd video), the ESP was turned on and came on all the time up to around 120 kph. With ESP turned off, the acceleration would have been better but I didn't have the chance to videotape it because of excessive traffic.