For me, the Porsche 956/962 is the all-time greatest. It won the 24h of Le Mans on it's first outing in 1982 and dominated it until 1987. It even continued on to win the 1994 race. I don't think any car has had such an extensive racing history.
What made it even greater was that teams would modify their 956/962's. This got to small changes to complete revamps of the original design. They all had a similar goal; increase front downforce and improve the rigidity of the monocoque. The original design wasn't very stiff, and quality would differ based on build date(Porsche would do a batch, and those that waited the longest before curing, degraded the quickest.). Also it's Flat 6 engine proved to be a disadvantage because it limited tunnel size. It's amazing that with all of that it still continued to win races all over the globe.
Out of all the 956/962's that raced, the Busby Porsche has got to be my favorite. Clearly inspired by the then dominant Nissan ZX-T
![Image](http://staticassets-hrd.appspot.com/hporh4idptz5s/699x436_crop.jpg)