I spent 11 years in Germany through the 80's and early 90's while in the Army. It's a while ago, but then the "average" cruising speed on the autobahn seemed to be in the mid 80 mph range. And yes there were various stretches where speed limits (usually 130 kph) were imposed when the road coursed through a major city or through a tunnel.
Driving on the autobahn required more attentiveness than generally needed in North America. In the US, the slower speeds on interstates unfortunately can lead to driver boredom, and in some cases accidents. Non existent lane discipline at least in the US, doesn't add to an enjoyable driving experience here. The strict 'drive right' rule in Germany, and the need to always be wary of much faster vehicles approaching on the left demanded a drivers undistracted attention. There is a reason I never saw a European made vehicle with cup holders.
Heavy trucks used to be limited by law to 100 kph on the autobahn. I don't know if that is still the case.
'Drive right', strict use of direction signals (which were AMBER by law), and the regulation forbidding use of fog lights in clear weather conditions (which is much needed in the US), in my opinion, made driving in Germany much safer than in the US. The fact that all German roads including the autobahn were always beautifully maintained, and vehicle inspection standards were strict and enforced, including heavy trucks, also was a significant part of that equation.