The JGTC years (1993–2004)

The JGTC (Japanese Grand Touring Championship)^[1] was established in 1993^[2][3] by the Japan Automobile Federation (JAF) via its subsidiary company the GTA (GT Association), replacing the defunct All Japan Sports Prototype Championship for Group C cars and the Japanese Touring Car Championship for Group A touring cars, which instead would adopt the supertouring formula. Seeking to prevent the spiraling budgets and one-team/make domination of both series, JGTC imposed strict limits on power, and heavy weight penalties on race winners, in an openly stated objective to keep on-track action close with an emphasis on keeping fans happy.

Super GT (2005–present)

The JGTC had planned to hold a race during the 2005 season at the Shanghai International Circuit in China, in addition to the existing overseas round at Sepang in Malaysia. However, holding the series in more than two countries would have meant the JGTC would lose its status as a "national championship" under the International Sporting Code of the FIA, and therefore could not keep "Japanese Championship" in its name. The series would instead be classified as an "international championship" by the FIA, and would therefore require direct authorization from it, rather than the JAF.

Initially, JAF announced JGTC would be renamed "Super GT World Challenge" with the goals of "challenge to the world", and "challenge to entertainment"; however, FIA prevented JAF from using it due to confusion of the suffix with "World Championship" (a higher level FIA recognition status) and a dispute with Sports Car Club of America, which ran Speed World Challenge since 1990.^{[citation needed]} On December 10, 2004, it was announced that new name of JGTC was confirmed as "Super GT". However, despite the name change and several attempts at holding a second overseas race, Super GT has continued to only hold one overseas race per year; in theory, it could regain its status as a national championship and return to JAF jurisdiction.

In 2014, Super GT and the German touring car series DTM announced the creation of Class 1,^[4] which would unify GT500's and DTM's technical regulations, allowing manufacturers to race in both series with a single specification of car. After some delays, technical regulations were fully aligned in 2020, with the GT500 category fully adopting Class One specifications.^[5] By 2021 however, DTM switched to a Group GT3 series due to massive manufacturer exodus. Super GT maintained the current technical regulations for GT500, though the "Class 1" moniker would no longer be used.^[6]

GT500

The top class in Super GT, GT500, is composed entirely of manufacturer-supported teams, representing the three biggest Japanese automobile manufacturers: Toyota, Honda, and Nissan.

Since 2014, GT500 cars have been powered by single-turbocharged, inline four-cylinder engines with two liters of displacement and producing over 650 horsepower. The cars are silhouette racing cars with purpose-built carbon fibre monocoques. The advancements in aerodynamics and horsepower, combined with an ongoing tyre war driving even higher speeds, have made the GT500 class the fastest form of production-based sports car racing today. The pace of a current GT500 car is roughly equivalent to that of the fastest non-hybrid Le Mans Prototypes.^[13]

For many years, the Nissan Skyline GT-R, the Toyota Supra, and the Honda NSX (NA1) represented their respective brands in GT500. Today, the three cars competing in GT500 are the Nissan Z (RZ34), the revived Toyota GR Supra, and the Honda Civic Type R (FL5). Other models, such as the Nissan Fairlady Z, Lexus SC 430, Lexus RC F, Lexus LC 500, Nissan GT-R, and the Honda NSX (NC1) have been used, as well as the Honda HSV-010 GT, a prototype car developed specifically for Super GT with its planned road-going variant having been cancelled.

In the earlier years of the GT500 category, a number of foreign manufacturers entered cars in the series, with varying success. The Porsche 911 GT2 and the BMW-powered McLaren F1 GTR are, to date, the only foreign cars to win the GT500 championship, when the former won the teams' title in 1995 and the latter won both titles in 1996. A longtail version of the F1 GTR would later score a race victory in 2001. The Ferrari F40, Porsche 911 Turbo, and Porsche 962. The last foreign-built car to enter the series was the Aston Martin DBR9, which fared poorly in its brief run in 2009 - illustrating the overwhelming advantage in raw pace that the GT500 class cars had over the FIA GT1 category cars that dominated the landscape in Europe; Team Goh, who entered the 1996 F1 GTRs, planned to enter a Maserati MC12 in 2006, but withdrew during testing for similar reasons.^[14][15]

In 2012, the GT500 regulations was changed in order to provide provisions for four-door vehicles, although none was run until Honda announced that the Civic Type R will replace the outgoing NSX in 2024.^[16] In 2010, front-engine, rear-wheel drive layout became the only permitted layout in the class, prompting Honda to initially replace the first generation-based NSX GT with the HSV-010. In 2014, Honda was granted a waiver to allow the NSX-Concept GT and NSX-GT (both second-generation based models) to run with a midship engine to match the road car's engine position; the waiver expired at the end of 2019 season with the implementation of Class 1 technical regulations, after which Honda was required to redesign the NSX-GT to accommodate a front-engine layout.^[17]

New GT500 cars were introduced in 2014 in preparation for the future Class 1 Touring Cars, including the first car in the class to utilize a KERS-assisted hybrid powertrain, the Honda NSX Concept-GT. Common aerodynamic regulations with the DTM were adopted, as was Class 1's turbocharged four-cylinder engine specification. Furthermore, the 2014 rules overhaul also increased the cars' downforce by 30%, while lowering costs. Aerodynamic development above a "design line" wrapping around the fenders, bumpers, and doorsills was restricted. Over sixty common parts were introduced, including the brakes, diffuser, and rear wing.^[18]

In response to increasing cornering speeds, another aerodynamic overhaul was introduced in 2017, lowering downforce by 25%.^[19] Furthermore, KERS units were banned, although the only manufacturer to utilize such systems, Honda, had already discontinued their usage in 2016.^[20] In 2020, Class 1 technical regulations were fully implemented, with the manufacturers introducing new cars to comply with the new rules. Aerodynamic development was further restricted, and a standardized ECU and suspension were introduced.^[21]

GT300

Unlike GT500, both works-backed and independent teams compete in GT300, so the field tends to be much more varied in terms of types of cars entered. As in GT500, the major Japanese automakers participate in this class, entering cars such as the Toyota Prius and Subaru BRZ, which comply with JAF-GT regulations. However, the GT300 class is predominantly composed of GT3-class cars from European manufacturers such as Audi and Mercedes, although Toyota/Lexus, Nissan and Honda are also represented in the class by GT3 cars. This reflects a growing interest in the series from European manufacturers, with Audi and BMW fielding works-supported entries. Toyota/Lexus, Nissan, and Subaru also campaign works-supported cars in the class.

The GT300 class used to host more exotic cars from the likes of ASL, Mosler, Mooncraft and Vemac, as well as detuned GT500 cars, such as the 2004 title-winning M-TEC NSX. However, starting in 2006, teams increasingly chose to campaign European GT cars instead, a trend that accelerated in 2010 with the introduction of FIA GT cars to the series. In response to the decline of locally produced entries from specialist manufacturers, the GTA worked with Dome to create the "Mother Chassis" (ja: マザーシャシー), a low-cost GT300 platform,^[26] with the first MC car entering the series in 2014. Mother Chassis cars utilize a standard Dome-produced tub and GTA-branded Nissan VK45DE engine, while maintaining the appearance of production cars such as the Toyota 86, Lotus Evora, and Toyota Mark X. The MC concept proved to be popular with independent teams, as well as competitive, with the Toyota 86 MC winning the GT300 championship in 2016.

Since 2006, Group GT1 and Group GT2 could race in GT300, and Group GT3 cars are able to enter GT300 since 2010 season. After the 2011 season, GTA announced GT1 and GTE cars are not eligible anymore with the intention of reducing costs, and adopted full GT3 rule.

One of the more unique GT300 competitors was the Mooncraft Shiden MC/RT-16, a Riley Daytona Prototype-based revival of the original 1977 Mooncraft Shiden 77 (紫電77).^[27] It competed from 2006 to 2012, narrowly losing the title in 2006, and winning the championship in 2007. Front-wheel drive cars such as the Mitsubishi FTO, Toyota Celica and Cavalier, a rarity in top-level circuit racing, are further examples of unique GT300 machines. They competed in their original configurations until the early 2000s, when FWD cars were being permitted to be converted to rear-wheel drive configuration. The FWD cars were mostly unsuccessful, failing to win any championships, although a Celica won a race in 1999 after a Porsche 911 was disqualified. Rear-wheel drive cars dominated the series until 2008, when an all-wheel drive Subaru Impreza developed by Cusco won in Sepang. An open top car, Renault Sport Spider, made a one-off participation in 1997, also with lack of success.

Hybrid cars first raced in the GT300 class in 2012, when apr introduced their Toyota Prius apr GT, and Team Mugen fielded a Honda CR-Z GT. Both cars were heavily modified from their production counterparts. The Prius was powered by a 3.4 liter V8 LMP1 engine, which worked in concert with production Hybrid Synergy Drive components; the CR-Z utilized a 2.8 liter V6 LMP2 engine and a 50 kW Zytek electric motor.^[28][29] Both the CR-Z and Prius were mid-engined, differing from their front-engined road-going counterparts; this resulted in the CR-Z's withdrawal after the 2015 season, as new regulations for 2016 stipulated that GT300 cars' engines were to be located in the same position as in their production counterparts. However, apr took advantage of a loophole in the regulations to continue to race their mid-engine Prius until 2018,^[30] when the team was required to build a new, front-engine Prius.^[31]

The development of GT300 cars is much more regulated than that of their GT500 counterparts; the GTA works with the Stephane Ratel Organisation to balance the performance of all GT300 cars via technical adjustments in order to create close racing.^[32] While the GT3 cars in the class are closely related to production cars, the JAF-GT machines differ from production vehicles to a greater degree, and in the case of the Mother Chassis cars, share little more than a badge and exterior styling with their road-going counterparts. While engine outputs are at a lower level than the GT500 cars, the GT300 cars still post competitive times and races are relatively tight when combined with GT500 traffic. As it is becoming increasingly more difficult for GT500 cars to overtake GT300s, the GTA may review the speed difference between the two classes in the future, especially if the pace of the GT300 cars continues to increase.^[33]

Success Weight

Perhaps the best-known performance balancing system in use in the Super GT is its Success Ballast system, also known as Success Weight and formerly referred to as "weight handicap".^[37] Weight penalties are assigned depending on a car's performance during the race, similar to systems used in the DTM and the BTCC. The system metes out two kilograms of ballast per point scored;^[38] it formerly added ballast based on qualifying positions and individual lap times. Stickers on the cars display every car's weight handicap level. In the 2007 season, the Takata NSX team achieved a record-breaking 5 pole positions in the first 7 races, but due to the weight handicap system, they only won one race among those seven. Such regulations keep the championship in play up to the final race of the season: only two GT500 teams (ARTA in 2007 and MOLA in 2012) and one GT300 team (GAINER with André Couto in 2015) have managed to clinch a driver's championship prior to the final race.

Following repeated cases of teams and drivers not winning a single race but still winning the championship (in 2003, neither the GT500 nor GT300 champions won a single race in particular), the handicap system was changed in 2009 to combat sandbagging, discouraging a team from intentionally performing poorly in order to secure a more favorable weight handicap. The ballast is now halved in the penultimate race and lifted altogether in the final race for teams that participated in every round of the season. Teams missing only one round receive halved-ballast in the final race instead.

In 2017, the weight handicap system for GT500 cars was amended to add fuel flow restrictions. Actual weight ballast will be capped at 50 kilograms for reasons of practicality and safety. When a car's assigned ballast exceeds 50 kilograms, it will be assigned a lesser amount of weight ballast, but a fuel flow restriction will be imposed, the severity of which increases according to the size of the assigned weight handicap. While the amount of actual weight ballast carried may vary, the weight handicap stickers on the cars will continue to display the assigned weight handicap.^[39][40]