Today we've been to Plauen. There we saw a special excursion of a tram.
I am pretty sure we did more things in Plauen than accidentally see an old tram car, but that seems to have been the most exciting thing to 8 year old me. I think it was one like in the little round picture above. The picture below shows cars as they were in use at that time.
Apparently you can book a ride in one of these old tram cars for 170 EUR an hour today.