The Mercedes European Delivery Center (read: car factory) offers a 90 minute guided tour every weekday. A crowd-pleasing mix of video car porn, crisply delivered factoids about Mercedes' storied past and close encounters with sensitive robots, it's all designed to provoke an intense desire for anything with a motor and a three-legged peace sign on the front.
Four tours a day are conducted in English for those more familiar with German engineering than the German language. Tour reservations can be made by phone--much more convenient than the schmoozing with a local luxury car dealer that is required to gawk at the insides of the neighboring Porsche factory.
Be forewarned though: While the free coffee and immaculate public restrooms may seem like backpacker's heaven, a good number of the other people taking the tour are there to pick up their new ride. Those with driver envy might want to sit this one out.