The Group CN regulations were established to provide a structured class for prototype sports cars that fell outside the traditional touring car or GT categories. The rules set boundaries on engine displacement, weight, and aerodynamic configuration, allowing constructors to build dedicated racing machinery while keeping costs broadly accessible relative to top-tier FIA sportscar classes. Group CM is a non-FIA class closely related to Group CN, catering to similar machinery under different sanctioning structures.
The Radical European Masters is a spec racing series in Europe based on Group CN regulations. It features purpose-built Radical cars — principally the Radical SR8, Radical RXC Spyder, and Radical SR3 — each assigned to their own class within the series. The series has been a major showcase for the British manufacturer Radical Sportscars, whose lightweight chassis and motorcycle-derived engines align closely with the Group CN performance envelope.
The French-based V de V organisation runs two FFSA Group CN-aligned classes. The endurance championship is open to any chassis and engine meeting the regulations, providing variety across the grid. Separately, the organisation runs the Funyo Challenge, a restricted class open exclusively to Peugeot-powered Funyo 4 or Funyo 5 cars, offering a more controlled entry point for competitors new to prototype racing.
From 2022, the Indian Racing League adopted Group CN regulations using the Wolf GB08 Thunder, a purpose-built prototype constructed to CN specification. The inclusion of Group CN machinery in the Indian Racing League represented a significant expansion of the class beyond its European heartland, bringing contemporary prototype racing to a new national series.
Group CN classes exist in numerous national championships. Many of these competitions feature Radical machinery as the dominant vehicle due to its proven compliance with the regulations. Notable examples include the Radical UK Cup (featuring the Radical SR3) and the Open España Prototipos in Spain. Individual national series often adapt the baseline FIA regulations to their own sporting and technical requirements.
The GT and Prototype Challenge, run as part of the Benelux-based Supercar Challenge, permits Group CN-classified cars to compete alongside GT machinery. Current competitors in this class include the Radical SR3 and the Norma M20 FC, reflecting the breadth of constructors who have developed CN-compliant prototypes for circuit and hillclimb use.
While Group CN originated as a sports car racing category, its lightweight and relatively unrestricted nature has made it particularly well suited to hillclimbing. The regulations allow competitors to field aerodynamically efficient, low-weight prototypes that can exploit the short-distance, high-acceleration demands of hillclimb events better than heavier GT or touring car machinery. Across European hillclimbing championships — including the FIA European Hill Climb Championship — Group CN cars regularly contest overall honours and class victories. The combination of high power-to-weight ratios and the ability to run slick tyres on purpose-built chassis makes CN prototypes among the most competitive non-unlimited machines in the discipline.