In 1990, the BTCC introduced a class for cars with an engine displacement up to 2.0 litres. These cars initially ran alongside a second class that continued to allow larger engines, but from 1991 they became the only cars eligible to compete. The Super Touring formula — featuring normally-aspirated four-cylinder engines, production-derived bodyshells, and eventually aerodynamic aids including front splitters and rear wings from 1995 — was later adopted by the FIA and became the basis for touring car championships across Europe and beyond.
The one-class format immediately attracted strong manufacturer commitment. Six manufacturers — BMW, Ford, Mitsubishi, Nissan, Toyota, and Vauxhall — entered factory-supported teams in the opening seasons. The competitive intensity drove rapid technical development and escalating costs. Alfa Romeo joined with its 155 in the mid-1990s, controversially appearing with a rear wing in 1994 that was ultimately ruled legal because the wing was a standard road-car fitment. Audi entered in 1996 with its four-wheel-drive A4 Quattro and won the title that year, the all-wheel-drive system providing a significant advantage in wet conditions that proved controversial. By the end of the decade, escalating development costs forced several manufacturers to withdraw, and only Ford, Honda, and Vauxhall remained through the 2000 season.
The era produced close, hard-fought racing that drew large crowds to circuits and strong television audiences. The BBC broadcast highlights of every race from 1988 through 2001, with commentator Murray Walker covering the series and some rounds shown live from 1997. The combination of recognisable production car models, multiple manufacturers in genuine competition, and high-quality drivers gave the BTCC enormous public appeal. Drivers of international calibre competed in the series, and the championship was recognised as among the most fiercely contested touring car series in the world during this period.
The aerodynamic era opened in earnest after 1995, when front splitters and rear wings were permitted following the controversy surrounding Alfa Romeo's factory-fitted wing the previous year. This accelerated development costs considerably. Audi's 1996 title with four-wheel drive prompted regulatory discussion, though the championship adapted rather than immediately outlawing the drivetrain configuration. The Super Touring formula was simultaneously being used in Germany's Super Tourenwagen Cup, various national championships, and provided the basis for the FIA's own international Touring Car World Cup event during the mid-1990s.
As costs spiralled and manufacturer participation contracted, the BTCC introduced new BTC Touring regulations for the 2001 season in an attempt to dramatically reduce the financial burden of competition. The Super Touring era formally ended after the 2000 season. Looking back, participants and observers consistently identified the 1991–2000 decade as the championship's defining period — a time when genuine factory competition produced memorable racing, shaped the identity of the series, and elevated British touring car racing to international prominence. The Super Touring technical formula it pioneered went on to underpin the World Touring Car Championship when that series was revived in 2005.