The concept was developed by Stéphane Ratel, head of the SRO Group and promoter of the FIA GT Championship. The existing Group GT1 and Group GT2 classes demanded that manufacturers build and develop purpose-made racing cars, which drove up costs for both manufacturers and customer teams. GT3 was conceived as a simpler, more accessible alternative: by combining existing race cars from one-make series — such as the Porsche Supercup and Ferrari Challenge — alongside other available competition machinery like the Aston Martin DBRS9 and Dodge Viper Competition Coupe, all competitors could be kept closely matched through a Balance of Performance system managed by the FIA. A similar category using the same name had already operated in the British GT Championship.
The FIA prepared regulations and homologations in time for the 2006 season, when eight manufacturers were represented at the first Balance of Performance test ahead of the debut of the FIA GT3 European Championship. That first season also saw the International GT Open, British GT Championship, Spanish GT Championship, and Italian GT Championship each create dedicated GT3 categories. In 2007 the SRO expanded the concept by launching the Brazilian GT Championship and the German ADAC GT Masters as exclusively GT3 championships; the British GT Championship dropped Group GT2 and promoted GT3 to its headline class. The French FFSA GT Championship also added a GT3 category.
The Australian GT Championship joined in 2008, and the VLN Series and 24 Hours Nürburgring introduced GT3 classes in 2009. By 2011, GT3 machinery was winning outright at major endurance events including the Bathurst 12 Hour, Dubai 24 Hour, Malaysia Merdeka Endurance Race, and Spa 24 Hours, followed by a 24 Hours Nürburgring outright victory in 2012. The Blancpain Endurance Series was established in 2011 as a dedicated international GT3 endurance championship.
GT3 cars must be based on mass production road car models available for sale at the time of homologation, though this requirement does not necessarily extend to the engine. The BMW Z4 GT3, for example, used the 4.0-litre V8 from the BMW M3 E92, while the Mercedes-AMG GT3 employed the 6.2-litre V8 from the SLS AMG GT3. Beyond this base-car requirement, the regulations impose very few restrictions on engine size, configuration, or chassis layout, allowing a wide diversity of machinery to be homologated.
Performance equalisation is handled through Balance of Performance, administered either by the FIA GT Bureau or by the individual series. Targets are set to keep cars between 1,200 and 1,300 kilograms with power outputs between 500 and 600 horsepower, producing a broadly similar power-to-weight ratio across the grid regardless of whether a car achieves it through high power and high weight — like the Mercedes-Benz SLS AMG — or through lower power and lower weight, like the Porsche 911 GT3. All homologated cars must feature traction control, ABS, and built-in air jacks.
From March 2018 onward, a minimum production requirement applies: ten units must be built within twelve months of homologation, rising to twenty within twenty-four months. Homologations are valid for seven years and may be renewed by application; expired homologations can still be used in national series under local approval or in historic events.
GT3 spread to North America when the Rolex Sports Car Series admitted several GT3 cars with specification wings. The Japanese Super GT and Super Taikyu Series also adopted GT3, with Nissan becoming the first Japanese manufacturer to offer a customer GT3 car. When NASCAR merged the Grand-Am Rolex Sports Car Series with the IMSA American Le Mans Series to form the United SportsCar Championship, the GTD class accommodated GT3 machinery; from 2016 that class became GT3-exclusive.
Following the collapse of manufacturer support for their Class One touring car regulations, the Deutsche Tourenwagen Masters adopted the GT3 formula in 2021, marking a significant departure from the series' touring car heritage. In 2022, the FIA confirmed that the GTE class in the FIA World Endurance Championship would be phased out in favour of GT3 machinery competing as the LMGT3 class. This change took effect from 2024, allowing GT3 cars to contest the 24 Hours of Le Mans for the first time under the FIA WEC banner.
As of April 2026, 59 vehicles have gone through the FIA homologation process, though some were not completed or were later revoked. Nineteen vehicles held valid homologation as of January 2026. Cars can be constructed directly by automobile manufacturers or by racing teams and tuning companies appointed by manufacturers. Various national-level homologations have also allowed additional machinery — including the Ginetta G55 GT3, Radical RXC GT3, and Scuderia Cameron Glickenhaus SCG 003C — to compete alongside standard FIA-homologated GT3 cars in certain championships.
In less than two decades, Group GT3 became the de facto global standard for GT racing. Its combination of accessible costs, competitive Balance of Performance, and technical diversity made it attractive to manufacturers, customer teams, and series organisers alike. The category now operates as the premier or a leading class in dozens of championships across six continents.
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