I think you'll be disappointed. The notion of a German Autobahn being in any way "unique" is just a myth.

True, there is no national speed limit, but...

- there are speed limits on many individual stretches of Autobahn
- even when there is no speed limit you'll rarely be able to do more than about 90 mph because there is so much traffic
- you should also be aware that if you do more than 130 kph/80 mph (the "recommended speed limit"), and you are unlucky enough to be involved in an accident, then the fact that you were exceeding the recommended speed limit will count against you insurance-wise

Drive by all means... but if you're expecting something special or different you'll be disappointed.