So one of the highlights was picking up new BMW-once in a lifetime experience. BMW museum also worth seeing. Driving for the most part easy but we left car in garage/car park when in cities. Definitely need safety vests for all passengers in Austria (gas station at German border selling them like hotcakes)-people really put them on at roadside breakdowns! (After lighting up a cigarette). I had Intntl Driving permit but never had to show it. Toll stickers for Austria and Czech avail at gas stations. True there is no speed limit on parts of German autobahn but heavy truck traffic made it hard to go fast for any length of time. BMW man told us AUstrian police very happy to give out tickets; speed cameras abundant on both Austrian and Czech highways. Most drivers more courteous than many parts of US as long as you get out of passing lane quickly. I was worried about damage from recent floods but only long detour we had to make was getting to Halstaat from salzburg(road washed out)-had to take teeny two lane road over mountains but GPS got us there. Overall, having a car was a great way to see these countries.
"True there is no speed limit on parts of German autobahn but heavy truck traffic made it hard to go fast for any length of time." Welcome to the dirty secret of the famous Autobahn network! "BMW man told us AUstrian police very happy to give out tickets;" BMW man speaks the truth on that point.
So perhaps driving your own car or especially your own BMW (if you're into that kind of thing) made the driving experience better for you.