BMW 320i STW-BTCC

Modeled after the 2 Litre Touring Car category introduced in the British Touring Car Championship in 1990, FIA Class 2 was designed to put a stop to the tremendously expensive homologation process and increasingly complex designs seen in Group A. Ironically, despite this conservative attitude, the class would come to be known as "Super Touring".

BMW had entered a two door version of its new E36-generation 3-Series in 1992, badged as a 318iS despite the two liter engine. This was done out of sheer necessity, as the 320i was a six-cylinder car, and BMW wanted to use the ready-made S14 four cylinder engine from the E30 M3, instead of trying to convert the big, long and heavy six into a competitive race motor.

The updated 320i picked up right where its predecessor left off, with its S42B20 engine derived from the road M42. The racing version of the M42 engine is called the S42 and was used in BMW's 320 4-door touring car, participating in the German Super Tourenwagen Cup. Compared with the M42, the S42 has individual throttle bodies, the displacement increased to 1,999 cc (122.0 cu in), two fuel injectors per cylinder, an increased compression ratio and a different cylinder head. The valve cover and airbox were made from carbon fiber and the lubrication system used a dry sump. In 1995, the initial version of the S42 engine produced 224 kW (300 bhp), increasing to 235 kW (315 bhp) for the final version in 1997.