Group GT3

Group GT3, known technically as Cup Grand Touring Cars and commonly referred to as simply GT3, is a set of regulations maintained by the Fédération Internationale de l'Automobile (FIA) for grand tourer racing cars designed for use in various auto racing series throughout the world. The GT3 category was initially created in 2005 by the SRO Motorsports Group as a third rung in the ladder of grand touring motorsport, below the Group GT1 and Group GT2 categories which were utilized in the SRO's FIA GT Championship, and launched its own series in 2006 called the FIA GT3 European Championship. Since then, Group GT3 has expanded to become the de facto category for many national and international grand touring series, although some series modify the ruleset from the FIA standard. By 2013, nearly 20 automobile manufacturers have built or been represented with GT3 machines.

GT3 cars must be based on mass production road car models that are being built and sold at the time of homologation, which does not necessarily include the engine (e.g. the BMW Z4 GT3 used the 4.0L V8 from the BMW M3 E92, while the Mercedes-AMG GT3 the 6.2 V8 from the Mercedes SLS AMG GT3). Apart from that, Group GT3 allows for a wide variety of car types to be homologated with almost no limit on engine sizes and configurations or chassis construction or layout. Performance of all the Group GT3 cars are regulated, either by the GT Bureau of the FIA or by a series' specific ruling body, through the balance of performance formulae that adjusts limits on horsepower, weight, engine management, and aerodynamics to prevent a single manufacturer from becoming dominant in the class. The cars in GT3 are designed to have a weight between 1,200 and 1,300 kilograms (2,646 and 2,866 lb) with horsepower between 500 and 600 horsepower (507 and 608 PS; 373 and 447 kW). All cars have a very similar power to weight ratio but achieved either by high power and high weight such as the Mercedes-Benz SLS AMG or low power and low weight such as the Porsche 911 GT3.