I think it was 297 that my 2014 v8 topped out at on a highway. I also find it much easier to go fast in Germany than the usa as people follow the rules. In the usa some people drive in the left lane on a empty flat highway at 90. And no one here expects a driver to be doing 220. One thing I learned driving so much in Germany was to really watch my mirrors for cars coming up behind me. The rate of closing can just be so fast that my brain was not trained to look for cars approaching so fast.
I've spent most of my time in Bavaria, but did drive up to Silt (and then put car on that train) one time. Those northern roads that the Fischkaufer's have seem to be better for high speed driving.
Man, I have a lot of good memories of trips to Germany over the years. So many good family run hotels of super high quality.