Peter Gregg was the IMSA driver every one strived to beat. He started in the early ‘70s with Porsches and had done very well. He won the first championship in 1971, sharing a Porsche with Hurley Haywood in the GTU class (under 2.5-litre). By 1973 he was running the iconic Porsche Carrera RSR and he would win the IMSA title in 1973, 1974 and 1975. By then he was known as ‘Peter Perfect,’ always approaching his racing in a very professional way, trying to leave nothing to chance. In 1976, on one occasion IMSA would not allow the 934 to run, and he realised that the RSR would struggle, and so switched to the factory BMW CSL. He was beaten to the title by Al Holbert in a Chevrolet Monza. By 1977 IMSA had decided to allow a 934 ½ to run, but this was no ordinary 934, this was a specially made 934 with some permitted changes, sort of like a 934 on steroids.
Peter Gregg showed up with one of these at Sebring and promptly sold the car to Jim Busby, as he had a second new one on the way. They managed to finish third behind two RSRs due to losing a wheel. By Atlanta, he had his own car and caused quite a stir, when he was several seconds faster than anyone else. IMSA found the car to be totally out of 934 ½ specification and sent him home, and the car did not race. He then proceeded to run the season in the Trans Am Championship and won the series, but was subsequently stripped of the title by the FIA due to rules irregularities.