The conceptual roots of STI stretch back to 1972, when Subaru entered the Leone in Australia's Southern Cross Rally. A more tangible precursor came in 1980, when the Leone 4WD became the first AWD car entered in the World Rally Championship, competing in the Safari Rally. Subaru Tecnica International was formally established in 1988 by Noriyuki Koseki and Ryuichiro Kuze, with a brief to professionalise Subaru's motorsport operations.
One of STI's first major undertakings was a world endurance record attempt in January 1989. A fleet of three modified Subaru Legacy RS sedans covered 100,000 km at an average of 223.345 km/h, setting the FIA World Land Endurance Record. The Legacy RS used a 2.0-litre EJ20 turbocharged engine; STI tuned the suspension and aerodynamics for the attempt. That November, Subaru released a limited-run Legacy RS Type RA road car incorporating many of the same modifications.
STI partnered with Prodrive of the United Kingdom in 1989 to develop a rally-ready vehicle based on the Legacy chassis. The resulting Legacy RS was homologated for FIA Group A competition and first campaigned in the 1990 WRC season, finishing fourth in the constructors' standings. Colin McRae joined the Subaru World Rally Team in 1991, and the team won three consecutive British Rally Championships between 1991 and 1993. The Legacy RS scored its first outright WRC win at the 1993 Rally New Zealand.
From 1992, Subaru began developing the smaller Impreza WRX as its next rally weapon. Homologated for Group A competition as the Impreza 555 and prepared by Prodrive, the car debuted in the 1993 1000 Lakes Rally with Ari Vatanen taking second place. The Impreza 555 delivered three consecutive WRC constructor's championships for Subaru from 1995 to 1997, a period during which drivers including Colin McRae and Richard Burns gave the blue cars their defining identity.
In 1994, STI began marketing the WRX STi road car derived from the rally program. A landmark special edition arrived in 1998 when STI produced the 22B to celebrate the championship hat-trick and Subaru's 40th anniversary: just 400 examples were built, reputedly selling out in 30 minutes. The 22B initiated the S-line family of limited-production performance cars, followed by the S201, S202, S203, and S204 in successive even years.
Subaru withdrew from the WRC at the end of the 2008 season, citing the global financial crisis.
The WRX STI sold in North America from the 2004 model year carried the 2.5-litre EJ257 engine, distinguishing it from the Japanese domestic market 2.0-litre EJ207 specification. Standard equipment on STI models across generations has included Brembo brakes, Bilstein suspension, BBS wheels, a driver-controlled centre differential, and a six-speed manual gearbox. Recaro-style bucket seats and a MOMO steering wheel have been recurring interior signatures.
STI trim has been applied beyond the Impreza: Legacy models received full STI specification in limited Japanese and New Zealand markets, with S401 (2002) and S402 (2008) variants produced in runs of 400 and 402 units respectively. A Forester STI II Type M appeared in 2001, limited to 800 units with 250 PS output and extensive chassis upgrades.
STI entered the Nürburgring 24 Hours in factory form from 2008 onward, competing in the SP3T class for turbocharged production-derived cars. The WRX STI took SP3T class victories in 2011, 2012, 2015, 2016, 2018, and 2019, building a significant record in the endurance classic despite the category's demanding pace. The 2017 car retired from a podium position due to an engine fire.
STI has competed in the GT300 class of Japan's Super GT series since 2009, initially with the Legacy B4 GT300 before transitioning to the BRZ GT300 from 2012. The Subaru BRZ GT300 claimed the series championship in 2021, the team's first Super GT title.
At the 2022 Tokyo Auto Salon, STI unveiled the E-RA Concept, an all-electric racing prototype featuring four motors — one per wheel — with a combined output of 800 kW and 1,100 Nm of torque. The motors were developed by Yamaha Motor Company. The E-RA was designed to meet FIA Electric GT Championship specifications, signalling STI's intention to translate its motorsport heritage into electrified competition.