So, heres a german guy, let me tell you this
:
Germanys highways are called "Autobahn", which usually have 2-3 lanes per direction. On some parts of the Autobahn you have a speed-limit, usually ranging from 100-130km/h (~50-65mph), especially around interchanges and big cities. Around highway building sites u have an even lower limit around 60-80km/h.
When you drive and you see this sign
View attachment 3316625
it means you can drive as fast as you want, AS LONG AS the circumstances (weather, traffic density, etc) allow to do so.
It is also expected from drivers to drive on right lanes and only switch lanes for overtaking others. So if theres three lanes and you choose to cruise with 120km/h on the middle lane permanently, and dont swerve back to the right lane when gaps are big enough, then you are driving wrong.
Germany has about 13200 kilometers of Autobahn. 57% are without speed-restrictions, while 30% have a permanent speed-limit, and 12.8% having speed-limits due to construction sites.