@Marjorie: BMW got to Eisenach as they took over the brand Dixi. Dixi made the Austin 7 in licence for example. Nothing to do with preparation for war. Stronger still, they got there before Hitler came to power. EMW did more then just change the name. The logo changed a bit as well, blue being replaced by red. EMW is for Eisenacher Motoren Werke (translates to something like Eisenach Motor Factory).
@Mark: I am wondering how they could have used a rocket before rockets took of...

Porsche had the idea of Volkswagen long before Hitler came to power. The name Volkswagen and even some of the design idea's came from another German carmaker, "Standard" which advertised with "Das deutsche Volkswagen". Later they were paid a sum of money.

Armand Peugeot actually had to set up a seperate company to sell cars. The family did not mind he used the name Peugeot. When the other company also started making cars, they did so with the name "Lion-Peugeot". Around 1916 Armand Peugeot's company would take over the iolder family business, although they still make the grinders. Strangely, you will get that one thing that no car manufacturer puts on their cars, a life-ling warranty.