The SR3 lineage began in 2002, designed by race car designer Mike Pilbeam as a further development of the Radical Clubsport 1100. The car was originally developed for participation in FIA international competitions in the C3 class. Built around an extremely lightweight trellis chassis, the SR3 weighs less than 600 kg, and its aerodynamic package generates sufficient downforce to sustain cornering acceleration of up to 2 g at high speed.
The RSX designation — introduced in Autumn 2014 — marked a significant revision of the SR3 formula. Like the SR3 RS variants before it, the RSX uses the Suzuki Hayabusa 1300 engine as its powerplant. The car is available in left-hand or right-hand drive configuration, catering to international markets and a wide variety of racing series. The RSX does not feature a roof or trunk, maintaining the open-cockpit character of the SR3 family. Racing bucket seats contribute to the car's weight discipline.
The SR3 RSX is powered by the Suzuki Hayabusa 1300 engine, shared with the SR3 RS 1300 and SR3 RS 1500 Turbo variants. The standard SR3 delivers 243 hp, with the optional Race Pack upgrade increasing output to 304 hp. The aerodynamic configuration of the car enables very high cornering speeds relative to its power output, making it competitive in multiple series and classes.
A separate road-legal variant of the SR3 platform exists, the SR3 SL (Street Legal), which uses a 2.0-litre Ford EcoBoost inline-four engine from the Focus ST and includes mandatory road features such as a heater, footwell lighting, and a 12-volt socket. The RSX is the dedicated track and racing version.
The SR3 RSX is eligible to compete in a wide variety of national and international racing series. Radical Sportscars operate or support dedicated one-make Radical Cup series across multiple regions including the United Kingdom, Europe, North America, the Middle East, Asia, and Australia. The global footprint of the Radical Cup series makes the SR3 RSX one of the most widely raced cars of its class worldwide.
The SR3 platform's blend of low weight, aerodynamic grip, and accessible power makes it particularly suited to club racing and driver development, while the RSX specification raises the ceiling of the platform toward more professional competition. Drivers transitioning from karting or lower-formula categories have used the SR3 RSX as a step toward professional motorsport, given its demanding handling characteristics relative to its modest displacement.
The Radical SR3 is considered the brand's most successful model by sales volume, and the RSX update ensured the platform remained competitive against rival manufacturers entering the lightweight sports-prototype segment. With over 1,100 SR3 units sold across all iterations, the lineage spanning more than a decade of continuous production represents one of the most enduring manufacturer-supported racing car programs in club motorsport. The SR3 RSX continues the tradition of providing a race-ready, purpose-built machine accessible to amateur and semi-professional drivers through a global support and series network operated directly by the manufacturer.