In December 2010, McLaren announced that they would produce a small number of MP4-12C cars in order for them to compete in the FIA Group GT3. McLaren stated that they will provide maintenance for the cars and will begin racing in 2012 with the CRS Racing team. The MP4-12C will be the first car to compete in sportscar racing for the company since the F1 GTR. It received its début with a single car entry for the Spa Francorchamps round of the British GT championship. This was followed by a three car entry in the 2011 Spa 24 Hours. Another car was also entered in the GT cup of the 2011 Macau Grand Prix, driven by Danny Watts.
In March 2012, McLaren readied 25 MP4-12C GT3 cars for a full racing season in the 2012 FIA GT1 World Championship, and its GT drivers tested the car on its Dunsfold test track, the same test track as used in the Top Gear BBC television show. McLaren released several promotional videos for the MP4-12C in the lead up to the racing season, including one of Formula 1 star Lewis Hamilton driving the car at locations in the U.S.
Compared to the road car, the MP4-12C GT3 produces less power with only 493 bhp (368 kW; 500 PS) due to homologation. The car features a new bespoke six-speed gearbox that is 80 kg (176 lb) lighter than the road car’s seven-speed, developed with Ricardo. The steering wheel is lifted from the McLaren MP4-24 Formula 1 car.
The car took its first victories in the world at the two races of the Circuito de Navarra round of the 2012 FIA GT1 World Championship season being run by Hexis Racing.