I had the pleasure of driving a K70 in the late '70s - it was a wonderful car. I remember the 8 small valve covers instead of one big and the disc brakes at the gearbox and not at the front wheels. The car was elected as car of the year over here which was fair since it really showed something new, many ideas was taken from the older brother RO80 which was even more ahead of its time:
http://en.wikipedia.org/wiki/NSU_Ro_80. (Imagine that the design of the RO80 was done in the early '60's and it looks more modern than many '80s cars!)
The K70 was wery well put together, high finish, lots of room, a wery dynamic engine. It shared some minor components with the 412 in the interior.
Still it had to leave in '75 - K70 it did not share anything with the new Audi/VW models Passat, Golf etc was one of the reasons, another was that it had wery much the same size as the Audi 100 and the Passat.
/Lars S