Originally Posted by
foama
When VW had only air-cooled engines and their products became low and lower in demand, NSU was developing a new little car with a totally new engine. Prior to that NSU already had some very fine small cars, such as the NSU Prinz, the Prinz TT and others. The result was a car completely different from anything VW ever had. Very shortly before development was finished, the historic brand Audi took over NSU. They were particularly interested in that new model to save themselves from folding. VW, which didn't have anything like it and was lacking a modern product, took over Audi. They inherited a production facility and a great modern product. That new car became an enormous sucess. It was initially marketed as the Audi 50, then as the VW Polo. After that came the Golf/Rabbit and others, all of similar concept. That NSU development became the foundation for the continued success of the VW group.
NSU pioneered the Wankel rotary engine. They had persistant problems with piston seals, and relatively high fuel consumption. They eventually gave up the Wankel engine, and MAZDA came in. MAZDA continued development, had a few brilliant ideas, and thoroughly changed a few things. The exhaust ports were designed totally different, as were the piston seals. Their developments were a huge improvement.