[bleucamaro]

If you take the train to Stuttgart, its really easy to get to the Porsche Museum, stop at the Hopfbahn Hoff (main train station), change to the U-bahn, and there is a stop at Porscheplatz.

Alternatively, rent a car and enjoy the fruits of the autobahn. And it's probably cheaper to rent a car. check out Sixt, they had good prices and interesting cars.

I agree with the comments about the Mercedes-Benz museum. It is a better museum than Porsche's, only the subject matter has a slightly different flavor.

Heidelberg is really cool.

The Sinsheim Museum is interesting also.