I am very well behaved re speed limits, I do enough miles and, I suspect, getting old enough, to appreciate driving defensively these days. (cue boring old fart music)
However, on a recent trip back from Berlin, early on a sunny sunday morning, no lorries, sod all traffic, I was hoping to max it. Unfortunately, where there was a straight empty road, there was also fog (see previous reference to early in the morning), so I have not yet managed to see what the actual reported top speed really is. Managed to get to 170 before I had to back down but there was still some left, though I suspect at that speed there is a significant difference between reported and actual speed. At lower speed my speedo seems to be around +5%.
Got another holiday in Germany planned later this year so might see if I can give it another go.