A hard limit is imposed on some vehicles:
60 km/h
Buses carrying standing passengers
Motorcycles pulling trailers
80 km/h
Vehicles with maximum allowed weight exceeding 3.5 t (except passenger cars)
Passenger cars and trucks with trailers
Buses
100 km/h
Passenger cars pulling trailers certified for 100 km/h
Buses certified for 100 km/h not pulling trailers
The German autobahns are famous for being some of the few public roads in the world without blanket speed limits for cars and motorcycles.
Speed limits do apply at junctions and other danger points, like sections under construction or in need of repair. Speed limits at non-construction sites are generally 100 km/h, 120 km/h, or even 130 km/h; construction sites have a usual speed limit of 80 km/h but may be as low as 60 km/h, or in very rare cases, even 40 km/h. Certain stretches have separate, and lower, speed limits used in cases of wet lanes or in order to reduce noise pollution during overnight hours (usually 10pm – 6am).