Mazda Motor Corp., the only maker of Wankel rotary engine-powered cars, tells WardsAuto.com it has suspended development of a next-generation powerplant because of cost and questions about the engine’s efficiency and exhaust emissions.
Mazda’s rotary-powered RX-8 sports sedan is scheduled to go out of production after the current model year. Ward’s notes that the status of the on-again, off-again next-generation RX model is unclear. At one point the company hoped to achieve a 30% improvement in fuel economy with the new Wankel over the 1.3-liter unit used in the RX-8.
Wankel engines replace the usual pistons and cylinder with a triangular rotor that rotates within an oblong container. Wankels are smaller and smoother than piston engines, but they’re also less efficient. General Motors Co. became very interested in the technology in the late 1970s but eventually abandoned its multi-million-dollar Wankel development program.
Mazda isn’t saying whether it will resume Wankel development later. But the company notes rotary engines could play a role in extended-range hybrid vehicles, where a small onboard gasoline engine is used to recharge the car’s battery but not drive the vehicle’s wheels. In those applications, the engine runs at steady load and speed. Powertrain engineering firm AVL List already has demonstrated a rotary engine in a BMW Mini Cooper modified to operate as a plug-in hybrid.