In Germany they advise a speed of 80mph, but there is no actual limit.
Not strictly correct. Only about 30-35% of the autobahn network is de-restricted, the rest is limited to 130kph (80mph). On the de-restricted bits if you have an accident and were doing over 130kph then they will examine your driving before the accident much more closely. They do still have cameras but mainly in the restrcited areas near towns and cities.
One thing to watch out for is when the big Mercs and Beemers, or whatever, do come rocketing past you will get a lot of buffeting, bit like passing a lorry on the motorways in the UK at speed, but in reverse.
As previously said, they’re very big on lane disicpline, so watch out for headlights rapidly approaching and if you’re not overtaking move back over or be prepared to be tailgated VERY close. I used to max out the Elise at 130 and still had people passing me as if I was at a standstill.