At the end of 1973, Roger Penske organized a televised one-make championship in the United States called IROC (International Race of Champions). The idea was to have a series of single-seater and endurance drivers take part in the championship at the wheel of Porsche Carreras. The championship took place between the end of 1973 and the beginning of 1974, mainly on the Riverside circuit. The cars for this championship had the 3-liter engine and the aerodynamic characteristics of the new Carrera RS. The IROC car had been prepared and lightened with details that prefigured some solutions later adopted in IMSA and TransAm. At the end of the championship, the cars were all sold, mainly to IMSA Camel GT teams, who adapted them to 1974 specifications.
The 1973-1974 IROC was won by Mark Donohue, recent CanAm champion with the Porsche 917/30. The last race of the championship was held in Daytona in February 1974, as part of the NASCAR 500 miles.
The Solido brand is one of the most important in the history of car modeling. Ferdinand de Vazelles of Nanterre (France) began producing die-cast models under the Solido brand in the early 1930s. The first creation was a Gergovia candle on wheels. Until the 1950s, Solido models were equipped with wind-up motors. In 1957 Solido introduced the 100 series with detailed 1:43 scale models, featuring several new gimmicks such as suspension and opening parts. In addition to contemporary vehicles, classic cars from the "L'age d'or" series were also reproduced from 1964. In addition to French production, Solido models were also made in Spain (Dalia), Brazil (Brosol) and Argentina (Buby) in the 1960s and 1970s. In 1980 Solido was taken over by Majorette and numerous other changes of ownership followed. From the 1980s onwards, reissues of old Solido models were released under the Verem brand. After the closure of the Oulins factory in 2006, all Solido models were produced in China. After Solido was taken over by Ottomobile in 2015, the company focused primarily on 1:18 scale die-cast models and moved production to the factory in Bangladesh. Since 2023, Solido has started to seriously invest in 1:43 again with a range of low-cost but excellent quality models.