As I was reading the forum for Austria, I noticed a lot of concern in traveling between Germany and Austria and also the reverse. these comments were from August-October 2015. I was wondering what the situation might be now. We are currently planning a trip for August 2016 and want to know what to prepare for. We will be driving.
In mid December I drove from Munich to Salzburg on the autobahn; no border crossing stop. When I did the reverse a few days later, the GPS did send me to an alternate route through Salzburg. The document check was set up on a bridge. Traffic slowed a bit, I held up my US passport to the window, and I was waved through without even coming to a full stop.
The American Embassy of Austria will post updates on their website concerning this. Last year you just had to wait 45min in traffic on the Salzburg side. The rest of the border check was quite minimal.