BMW M3 Powered By A Mazda Four Rotor Engine

Mazda rotary engines have a reputation for being relatively small and powerful at the expense poor fuel efficiency. They are starting to become popular with kit car builders, hot rodders and in light aircraft because their light weight, compact size, and tuning potential stemming from their inherently high power to weight ratio.
In auto racing, the displacement a Wankel engine is usually doubled for classing purposes. For calculating taxes in Japan, the displacement Wankel engines is defined as the equivalent 1.5 times the nominal displacement, so the 1300 cc 13B engines are taxed as 1950 cc.