Porsche Carrera Cup (sometimes abbreviated PCC) is a number of one-make racing by Porsche premier series competed with, initially Porsche 911 Carrera Cup, then later Porsche 911 GT3 Cup cars. The cars are specifically built by Porsche for one-make racing, but are visually and mechanically quite similar to road-registrable 911s of the same generation. There are three distinct tiers of racing, the top tier is the Porsche Supercup.
https://en.wikipedia.org/wiki/Porsche_Carrera_Cup