The first car, chassis R1, was completed in November 1972 and tested extensively by Porsche at Paul Ricard. Weighing in at 830kg, 70kg less than the 2.8, wider wheels dictated some minor suspension revisions, but the most important developments could be found in the engine bay. Three different engines were used during the 1973 season, initially Porsche's 308bhp Typ 911/72 unit from the 2.8 seeing service. These were soon replaced by a more potent 3-litre Typ 911/74 engine with 2993cc and 315bhp. Later on in the year, Typ 911/75 engines with 330bhp were used. Regardless of which engine was installed, the 3-litre prototypes were fantastically quick and on their day even capable of matching the tastiest sports racing cars. To begin with, the bodyshells looked almost identical to the 2.8, however, it wasn't long before these rolling laboratories with their super-lightweight panels began sprouting some wild aerodynamic devices. This was all perfectly legal now the 911 was freed from the homologation constraints of Group 4, wheels getting progressively wider as the year wore and in turn necessitating ever more bulbous fender flares. The 2.8's ducktail spoiler was soon replaced by a huge wraparound aerofoil. Looking absolutely stunning in silver Martini & Rossi liveries, the works cars were driven by some of Porsche’s best factory pilots, Gijs van Lennep, Herbie Muller, Leo Kinnunen and George Follmer all having starred. The year brought Porsche two outright victories in events they could hardly have expected to win, the RSR finishing first overall in its debut race, the Daytona 24 Hours (pictured top), and again in what was the last ever Targa Florio (below).

These extremely impressive results were backed up by top five overall placings at the Spa and Nurburgring 1000km race's whilst Florio victors Muller and van Lennep also finished fourth at Le Mans (see bottom). Eight RSR 'Prorotyp's were built, the chassis numbers of which are indexed below. To view the 3.0 RSR 'Prototyp's period race record, click on the appropriate link below to find information on the cars, drivers and teams who took part in that famous '73 season:

1973 World Manufacturers Championship
1973 Trans Am Championship