Have you ever been to Sinsheim? Its only about 35 minutes from Stuttgart. I really like that museum, bc it has so many different eclectic cars, trains, planes, tanks, tractors in it's collection. They also have a sister museum in Speyer, just South of Heidelberg (45 min from you).
Sinsheim Technik Museum
http://www.1addicts.com/forums/showthread.php?t=387433
See you guys tomorrow.