GT racing is filled with terms like GT1, GT2, GT3, and GT4, each representing a distinct class of cars governed by its own set of technical rules. These categories differ in performance, cost, and purpose, reflecting the sport’s evolution over the decades. From the extreme machines of GT1 to the accessible platforms of GT4, this explainer unpacks what each category means, how they relate, and why they matter in the world of motorsport.

GT1: The Original Top Tier

GT1 emerged in the early 1990s, first appearing in 1994 through the BPR Global GT Series. The series was founded by Jürgen Barth, Patrick Peter, and Stéphane Ratel (the organisation that would evolve into the SRO as we know it today) to revive high-profile sports car racing for production-based cars after the fall of the World Sportscar Championship. The FIA became involved later, and by 1997, the BPR Global GT Series evolved into the FIA GT Championship, an officially sanctioned world series that brought greater structure, global prestige, and wider manufacturer involvement to GT racing. It quickly became the world’s leading GT series, featuring major factory efforts and iconic endurance races that shaped the modern era of GT racing.

Initially, GT1 cars were heavily modified versions of road-going supercars such as the Venturi 600 LM, Porsche 911 Carrera RSR, and Ferrari F40 GT. As GT1 racing evolved, manufacturers began creating dedicated homologation specials. The McLaren F1 GTR, for example, was initially designed as a road car before customers persuaded McLaren to develop a competition version for Le Mans. In contrast, manufacturers such as Porsche and Mercedes-Benz built purpose-designed machines like the 911 GT1 and CLK GTR. Their road-going versions were produced only as an afterthought to meet homologation rules. These cars pushed the boundaries of the original GT1 spirit, focusing increasingly on performance and race-winning capability.

  • Technical: Extreme performance with powerful naturally aspirated or turbocharged engines, often exceeding 600 hp. Lightweight carbon-composite construction, advanced aerodynamics, and race-specific chassis. Built as homologation specials or race-first designs with minimal road car carryover.
  • Iconic Cars: McLaren F1 GTR, Mercedes-Benz CLK GTR, Porsche 911 GT1, Nissan R390 GT1, Maserati MC12.
  • Main Races: BPR Global GT Series, FIA GT Championship, Le Mans 24 Hours (GT1 class), Spa 24 Hours.
  • Timeline:
    • 1994: The BPR Global GT Series is launched by Jürgen Barth, Patrick Peter, and Stéphane Ratel, establishing the modern GT1 era.
    • 1997: The BPR Global GT Series evolves into the FIA GT Championship, becoming the leading international GT series.
    • Late 1990s: Costs spiral as cars become near-prototypes.
    • 2005-2010: FIA and SRO attempt GT1 revival, later relying partly on upgraded GT2-spec cars to fill grids.
    • 2010: GT1 effectively phased out; replaced by GT3-based series.

GT1 ended because costs became unsustainable, and fields shrank. In the late 2000s, the FIA and SRO tried to revive GT1 using upgraded GT2-spec cars. This underscored how the original GT1 concept had become financially and logistically unviable. Despite this, it remains iconic for its exotic, rule-pushing machines.

GT2: Two Eras, Two Meanings

Historic GT2 (1994–2023)

BPR introduced GT2 alongside GT1 in the BPR Global GT Series starting in 1994, intended as a category for more production-based cars at a lower cost compared to the extreme machines that populated GT1. While GT1 quickly escalated into a manufacturer arms race with heavily modified or bespoke prototypes, GT2 stayed closer to true road car origins, attracting privateer teams and smaller manufacturers.

As GT1 became unsustainably expensive by the late 1990s, many manufacturers and teams shifted their focus to GT2. The class grew in competitiveness and prestige, and when the FIA took over and formalised the FIA GT Championship, GT2 remained a crucial component. Throughout the early 2000s, GT2 flourished not just in Europe but also in North America, particularly through the American Le Mans Series (ALMS), where it became a fan-favourite class featuring fierce battles between marques like Porsche, Ferrari, and Corvette.

  • Technical: 450–500 hp with reduced aerodynamic grip compared to GT1. Steel or aluminium chassis, fewer electronic driver aids, and more reliance on production-car components. Maintained a closer link to road-going sports cars.
  • Iconic Cars: Ferrari 360 GTC, Porsche 911 GT3 RSR, Corvette C6.R GT2, BMW M3 E92 GT2.
  • Main Races: FIA GT Championship, Le Mans 24 Hours, Spa 24 Hours, American Le Mans Series (ALMS), FIA World Endurance Championship.
  • Timeline:
    • 1994: GT2 established alongside GT1 in the BPR Global GT Series as the second tier.
    • Late 1990s: GT2 grows as GT1 becomes increasingly prototype-like.
    • 1999–2010: GT2 becomes the leading GT class after GT1’s collapse.
    • 2011: GT2 forms the basis of the GTE category for Le Mans and WEC.
    • 2023: Final year of GTE at Le Mans and WEC as it is replaced by GT3.

When GT1 disappeared, GT2 became the de facto top class in GT endurance racing. The class later formed the basis for the GTE class at Le Mans and in the World Endurance Championship. It kept GT2’s production-based spirit but evolved into a more professional level of GT racing. However, as costs rose and GT3 grew in popularity, GTE gradually faded. Many GTE cars already shared design and technical similarities with their GT3 counterparts, making the transition more logical and less disruptive for manufacturers. This culminated in GT3 machinery fully taking over the top GT class at Le Mans and in the FIA World Endurance Championship from 2024 onward.

Modern GT2 (2019–present)

In 2019, the SRO Motorsports Group reintroduced GT2 independently of the FIA, but with a different philosophy. Modern GT2 cars are designed for gentleman drivers: they have more power than GT3 (up to 700 hp) but less aerodynamic downforce. Manufacturers such as Audi, Porsche, KTM, Lamborghini, and Mercedes-AMG developed dedicated GT2 models for this class.

  • Technical: 650–700 hp, low downforce, and simplified aero. Built on FIA-approved GT platforms with reduced cornering load but high straight-line speed. Designed for drivability and endurance, with advanced safety but fewer aero-sensitive setups.
  • Iconic Cars: Porsche 911 GT2 RS Clubsport, Audi R8 LMS GT2, KTM X-Bow GT2, Lamborghini Huracán Super Trofeo GT2.
  • Main Races: GT2 European Series, special classes within endurance events.
  • Timeline:
    • 2019: Modern GT2 category launched by SRO, aimed at gentleman drivers.
    • 2020s: GT2 builds its own niche with series like the GT2 European Series.
    • Today: Modern GT2 offers high-powered racing with less aerodynamic emphasis, sitting alongside GT3 and GT4.

Today’s GT2s are faster on the straights then GT3s but less demanding through corners, creating a driving style that rewards smoothness and straight-line performance — ideal for experienced amateurs seeking a high-speed but more manageable racing experience.

GT3: The Global Standard

GT3 was launched in 2006 by the SRO Motorsports Group, under FIA technical endorsement, to provide an affordable, competitive platform balancing privateers and professionals. Unlike GT1 and GT2, GT3 introduced heavy use of Balance of Performance (BoP) to equalise different cars’ capabilities.

Over time, GT3’s success grew to the point that it replaced older GT classes at the very highest levels. A major milestone came in 2024 when GT3 cars officially replaced the GTE (previously GT2) class in the FIA World Endurance Championship and at the 24 Hours of Le Mans. The new LMGT3 category took over as the top GT class in endurance racing, marking a full circle evolution: from the complex, high-cost GT1 and GT2 machines to the more balanced and globally adopted GT3 platform. This move was driven by a need to control costs, increase manufacturer participation, and unify GT racing standards worldwide.

  • Technical: 500–600 hp with moderate downforce. FIA-homologated race cars with carbon bodywork, ABS, traction control, BoP-managed performance, and endurance-grade electronics. Engine and drivetrain layouts vary (V8, flat-6, V10; mid/front engine), but lap times are equalised.
  • Iconic Cars: Audi R8 LMS GT3, Mercedes-Benz SLS AMG GT3, Mercedes-AMG GT3, Ferrari 488 GT3, BMW Z4 GT3, BMW M4 GT3, Porsche 911 GT3 R.
  • Main Races: GT World Challenge (Europe, America, Asia, Australia), Nürburgring 24 Hours, Spa 24 Hours, DTM, IMSA GTD, LMGT3 at Le Mans and WEC.
  • Timeline:
    • 2006: FIA GT3 European Championship launches.
    • 2010s: Global expansion, replaces GT1 and GT2 in prominence.
    • 2011: Blancpain Endurance Series launches.
    • 2011-2012: GT3 takes over the premiere class of the Spa and Nürburgring 24-hour races.
    • 2024: GT3 officially replaces GTE at Le Mans and WEC.
    • Today: Backbone of worldwide GT racing.

GT3 remains popular because it offers a balance between technical challenge, manufacturer involvement, and cost control.

GT4: Accessible GT Racing

GT4 was launched alongside GT3 by SRO as a lower-cost, entry-level category. GT4 cars are much closer to their road-going counterparts, with limited modifications.

The class quickly became popular worldwide, providing a strong grassroots and amateur racing foundation. The formula offers competitive racing at manageable costs, making it ideal for young drivers, amateurs, and teams operating on tighter budgets. Additionally, GT4 acts as a stepping stone, enabling drivers to gain experience before moving up to higher GT classes.

  • Technical: 400–450 hp with very limited aero and few mechanical modifications. Retains many stock components including the engine block, suspension layout, and interior elements. Standardised safety, BoP performance balancing, and lower operating costs.
  • Iconic Cars: Aston Martin Vantage GT4, BMW M4 GT4, McLaren Artura GT4, Toyota GR Supra GT4, Chevrolet Camaro GT4.R.
  • Main Races: GT4 European Series, ADAC GT4 Germany, British GT Championship (GT4 class), Pirelli GT4 America.
  • Timeline:
    • 2006: GT4 introduced by SRO as part of FIA GT4 Cup.
    • 2010s: Expansion across Europe, America, and Asia.
    • Present: Key step on the GT racing ladder.

In several national and regional championships, particularly where the GT3 market isn’t strong enough to sustain a dedicated top-level series, GT4 is often the premier GT category. Series such as the GT4 European Series, ADAC GT4 Germany, and Pirelli GT4 America feature robust, competitive grids. In multi-class series like the British GT Championship, GT4 provides a substantial and competitive sub-category alongside GT3 machinery.

How They Relate

In historical and performance terms:

  • GT1 was the top level: extreme, expensive, dominated by manufacturers, overseen by the FIA and SRO. Its main championship, the BPR Global GT Series, formed the basis for what is now the GT3-based GT World Challenge Europe.
  • Historic GT2 was a step below: semi-pros, closer to production cars, became top class briefly after GT1.
  • Modern GT2 targets gentleman drivers, organised mainly by SRO.
  • GT3 is today’s global racing standard: balanced, affordable, pro and amateur accessible, shaped mainly by SRO and FIA regulations.
  • GT4 is the grassroots platform: closer to road cars, focused on learning and cost control, promoted by SRO and national bodies like ADAC.

Today, GT3 and GT4 dominate the landscape, while modern GT2 serves a niche for high-powered amateur racing. Meanwhile, historic GT1 and GT2 machinery continues to captivate fans and plays a major role in classic endurance events and historic racing festivals, where these iconic cars are celebrated for their engineering and legendary status.

Evolution and Legacy of GT Racing

GT1 represents the wild early days of GT racing, filled with exotic, powerful machines. Historic GT2 provided a more grounded but still serious form of competition before evolving into today’s amateur-focused GT2 class. GT3 reshaped GT racing into a globally balanced, accessible category. It also played a key role in attracting young talents from top-level open-wheel series, helping to rejuvenate the sport and expand its fanbase. With lower barriers to entry compared to past GT classes and wide manufacturer involvement, GT3 made professional GT racing a viable career path for drivers outside the traditional endurance or touring car ladders, and GT4 opens the door to aspiring racers and budget-conscious teams. Together, these categories show how GT racing has evolved—keeping the spirit of road cars alive on the world’s most demanding tracks.

The groundbreaking concepts and ambition of GT1 paved the way for the development of GT racing. Through decades of innovation, challenges, and adaptations, the principles and lessons learned from GT1 led directly to the creation of today’s highly successful, sustainable, and globally embraced GT3 category. Together with GT4, it balances affordability, accessibility, and thrilling competition, continuing to attract new talents and maintain fan enthusiasm, ensuring the enduring popularity and longevity of GT racing worldwide.