I'm also experienced in the ways of the autobahns....
most are restricted to 120 or 130 kph - and incredibly annoyingly roadworks slow you down ridiculously. For example the A1 between Bremen and Hamburg is punctuated by contraflows - 6-8 miles stretches, 2 very narrow lanes each way and limited to 60-80 kph, then you have 2-3 miles of clear road until the next contraflow....
The older 2-lane stretches SGould mentions are the scariest - you could be doing 100+ quite happily and you can see about 2 miles ahead and there are 2 or more lorries - it is an absolute certainty one will engage in overtake... brake lights everywhere
Holland is worse - people just pull out, at least in Germany people wait for you to pass but people in their crappy Altos etc are empowered to drive how they like
But at least once they've overtaken they do pull back in
