Porsche has always believed in the value of racing cars to build better street cars, and nowhere is this more obvious than with the iconic Porsche 911. In the early 1970s, Porsche 911 Carrera RSR models were the cars to beat in GT racing, scoring victories in Daytona, at the Nürburgring and in the Targa Florio.

In fact, the 911 Carrera RSR chalked up seven German and three international championships in 1973, its debut year. Originally powered by a 2.8-liter flat-six engine rated at 300 horsepower, the displacement soon grew to 3.0-liters with an output of 310 horsepower.

The car (and its iconic duck tail rear spoiler) proved to be so dominant in GT racing that it was chosen to star in the inaugural season of the International Race of Champions (IROC) series, not to be confused with today's Race of Champions.

IROC pitted the top drivers of the day against one another in identically prepared cars, and the first season (run in 1974) featured stars like Mark Donahue, Bobby Unser, A.J. Foyt, Richard Petty and Emerson Fittipaldi, dicing wheel to wheel at Riverside International Raceway and on Daytona’s infield road course.

The Chevy Camaro replaced the Porsche 911 RSR in IROC competition after the 1974 season, but development of the racing 911 models continued. A turbocharged variant, the Carrera RSR Turbo, finished second at the 1974 running of the 24 Hours of Le Mans, ultimately paving the way for the 911 Turbo we know (and love) today.