As somebody who was using the Autobahn quite a lot I’d say most people go between 120 and 160 when there is no speed limit. But it depend on the conditions

Admittedly, the 160 was exaggerated. But as a German who does obey the speed limit, my experience seems to be that most drivers don't.

Because you never notice all the other cars that do. They travel as fast as you, so their distance remains constant. You only notice cars going slower or faster than you.