From my own experience driving there, I noticed that the average speed on the left lanes are usually around 160 with faster cars around 180.
But the truth is that with the traffic, it is very rare that you can go fast because when there start to be a reasonable amount of cars there is no way you can go too fast without doing slaloms. So speed is more low in real average.
I also noticed that people were driving more seriously and safely than in other countries because of the no speed limit:
In France for example, some people will go very fast in a dangerous way like an race, because of the thrill of being outlaw or something like that. Otherwise, everyone will try to be stuck to exactly 130 or a few km/h more to be exactly on the limit. Reluctant to slow down when needed and having difficulties to overpass cars that are just a bit slower without exceeding 130.
Another surprising fact is that, in Germany, when there are speed limits, they are usually lower than in France and very strictly enforced. Like driving at 30 km/h on streets crossing villages.