It's an easy and fun drive, if you are going you may as well visit the Nurburgring too. I think next time I'd fly though, (Fly to Hanover and get a taxi or train) as we didn't use the car at all for the few days we were there. Spent all our time in the Autostadt.
....What!!?? 
And miss the joy of driving in Germany? I think it's one of the best countries in the world for driving - You only live once AFAIK.
Take a car and also visit Berlin - It's a great city, not to be missed.
Thanks Red, and yet again I find myself agreeing with you. 
I love Germany, the people are v nice, the place is spotless compared to other parts of Europe, and their road manners are impeccible. I've toured there quite a bit and have done the Nurburgring, Baden Baden, Black Forest etc, but this is a place I think
is on my list next. I'm a bit of a WW2 enthusiast as well (where I live was occupied by the Jerries), I drive past concrete bunkers every day as a reminder of it.
I reckon my 2 weeks next year could be
D Day landings, (again)
Nurburgring (again)
Berlin (never been!)
Autostadt and possibly Ingolstadt
Austria
Eagles Nest
Bavaria then home.
As a seasoned traveller, what do ya reckon ?
....If you visit Berlin, consider taking an open top double-decker tourist bus - You really will see a lot and you can get on and off it en route. The remains of The Berlin Wall and also Hitler's sites have a very strong atmosphere and presence.
I've written up a trip I did to Bavaria-Austria-Italy here : -
http://biali.ritey.com/forum/index.php?topic=65.0 I haven't written up my drive to Berlin - it was only meant to be a weekend but I ended up in Bavaria! That's what's so great about travelling by road - You have that freedom.
