Porsche Carrera GT

Porsche began developing the Carrera GT in 2000 as a successor to the 911 GT1 car they had discontinued in late 1998 because of FIA rule changes. However, there was speculation that Porsche discontinued development at the behest of VW/Audi chairman Ferdinand Piëch - Piëch was reportedly concerned over the prospect of a Porsche vehicle competing against the Audi R8 race car, which had just been introduced. As a member of the Porsche family, Piëch holds a seat on the company's board of directors and owns a percentage of the firm, so his influence could be exacted from inside. In addition, Porsche needed to free up capital and manpower for development work on the Cayenne, and dropping development of the race car made it possible.

More information:
http://en.wikipedia.org/wiki/Porsche_Carrera_GT
http://www.conceptcarz.com/vehicle/z8455/default.aspx