Click
here, or on the tank for more info:
Also check out
this link, and
this one.
Here's a picture of Porsche (in the hat) next to one of his tanks.
Apparently, Porsche was a pretty poor tank designer. Most of his designs didn't make it past the prototype stage, and all of them were plagued with mechanical problems -- and they were far heavier than most of their competition (?!).
Although the two- and three-man tank models they built concurrently with the 964 (between 1989 and 1992) were a lot lighter and more successful.