Rennsport, or RS, was a moniker given to a special class of Porsche. It started with the 550A- RS Spyder, then moved eventually to the 1957 718 RSK, and various 718s of the very early 1960s: the legendary hill climbers. There are RS models like the 991 GT3 RS and most recently the 2022 718 GT4 RS that boggles the mind and quickens the pulse. But possibly the granddaddy of them all and arguably one of the most collectible Porsche's of all time is none other than the lightweight, ducktail,  911 Carrera RS 2.7 of 1973.