Sauerkraut is less popular in Germany than the rest of the world thinks it is. That said it is still very delicious when served with fried potatoes and onions and a nice slice of Kasseler (a special kind of cured and smoked pork chop), a little bit of mustard and a couple of ice cold Pilseners - yum.
No, the national dish in Germany of course is Currywurst: A bratwurst with or without peel, sweet and hot sauce (every good snack bar has its own recipe) and curry powder. It usually comes with a roll or chips. The most famous Currywurst is served in the Volkswagen staff canteen. Thousands are consumed each day. The wurst and the sauce have their own official VW parts numbers.