Wife and I went to Germany for our honeymoon also. The Germany part involved all things cars and LEGO Land. First thing we did the day after landing in Dusseldorf was the Nurburgring. We had a rental through RSR Nurburg, basically their slowest car (Renault Clio, no roll cage or five-point harness) for 10 laps and split the laps 50/50 between the two of us. We also ponied up for an instructor on the day of, even though we tried to learn the track as much as possible with Grand Turismo which helped but the instructor provide a lot of advice in terms of turn in points and recognizing certain markers on the track itself. Our day there also was with Destination Nurburgring, so it wasn't a tourist day. Plenty of really fast cars and drivers, fastest being a race-prepped Aston Martin that day which was pretty awesome to see. Only one incident that day. Did get a ride in a track prepped GT86 (Koni suspension, exhaust, interior strippped, etc.) that day as a coworker came in from Belgium and rented one, really liked how it handled especially around the corners. Met Sabine Schmitz there also as she was doing ride-alongs in her Porsche with RSR Nurburg. Highly recommend RSR Nurburg, great group of people there.
Frozenspeed was there also (along with a number of other photogs), never did get around to buying the original photo but apparently I still can.
Other things we did in Germany... Audi, BMW and Mercedes museum along with a factory tour at both Audi and Mercedes. We could have done BMW but the english tours were all booked (you couldn't get in the other non-english tours due to safety requirements). Didn't get a chance to do Porsche, next time though. Other things we did...day at LEGOLAND Deutschland, hike around Berchtesgaden National Park (reminds me a lot of Banff), and Eagle's Nest.