The International Race of Champions, the brainchild of Roger Penske, has been devised to pit the very finest drivers from a number of different disciplines against each other in identical Porsche 911s, at four events – three at Riverside, and a ‘season’ finale at Daytona. While the entry list is populated by a host of great names such as Emerson Fittipaldi, Denny Hulme, Richard Petty, and Peter Revson, it is the comparatively lesser-known Mark Donohue who will become the first IROC champion after winning three of the four races. Note the colourful cars’ ducktail spoilers. They will be removed come race day, and replaced with the ‘tea-tray’ unit found on the new 1974 model-year 911s. After all, this is an effective marketing tool for Porsche – not just a free-for-all death match on the racetrack. That’s why they’re resplendent in bold shades, so as to stand out on viewers’ new colour television sets. 

Photo: Porsche Archive