I just got back from my second trip to Germany, and really my first that I got to experince more than work/hotel/work/hotel...

I was in Schwarzenfeld (small village north of Regensburg) for a couple days, Regensburg Thursday night, Munich Altstadt Friday night, and headed out of MUC Saturday afternoon. What I learned:

Car & Navigation System:
Learn how to use the NAV system and set your destination BEFORE you pull out of the parking garage in MUC. Also make sure you have the English CD. The CD was not in my car, but it was not a big deal as I paid more attention to the display. It was somewhat complex to learn and I would forget what buttons to hit to change options and add new destinations - not something you want to be playing with on the autobahn at 200 kmh. Also realize that Point of Interest names may not be what you expect. I could not figure out how to set it to the Munich airport because the system listed it as "Flugenhafen Munchen" - finally found it by searching for local airports. I knew the way, but it would have saved me a wrong turn or two if I had it set before leaving the hotel. Even if you are used to miles, leave the settings in metric - much easier if your nav system distance matches the road signs.

I had a brand new Opel Astra with only 14 kmh - actually downgraded from an intermediate manual transmission I had reserved to get the automatic - didn't feel like trying to remember how to drive a stick after 13 years or so without. Make sure you check it over very carefully before leaving the lot. Upon return the check in woman spent at least five minutes going over every spec of dirt to see if it was a scratch. There was a small one on the rear bumper but she said it could be old. Doubtful since I was the first renter ever. Note this was National.

Autobahn
As already mentioned, STAY RIGHT. If you pass a truck or slow car, make sure there is A LOT of distance between you and anyone in the left lane behind. A fast Mercedes or BMW can close the distance in no time - had cars on my bumper in seconds with lights flashing that I never saw behind me.

My only drives have been to/from the Regensburg area, but once out of MUC it moves pretty good with many no speed limit zones. I got it up to about 190 kmh. After awhile the novelty wore off and I found it easier to hang in the right lane around 140. Driving fast does require a lot more concentration, and I would rather relax when driving. No potholes was very nice.

Munich
Traffic was bad getting in and out of the city due to the construction mentioned - took about an hour to get to the aiport Saturday morning - not counting my missed turns. I stayed at the Four Points Central and walked to the Altstadt - about 30 minutes. Ended up at Killian's Irish pub and was "trapped" by a rainstorm and didn't explore much further. Ended up taking a taxi back. One smart thing I did was take the hotel address - one of the note pad pages from the room. Just handed it to the taxi driver instead of trying to explain "which" Sheraton.