4 Reasons Why The Rotary Engine Is Dead

4 Reasons Why The Rotary Engine Is Dead. The Wankel engine was last seen in a production car in the Mazda RX-8, and currently there are no rotary engines in production. Mazda may bring it back in the RX Vision, however there are many disadvantages to the rotary engine which has kept it from being successful. Rotary engines have a low thermal efficiency as a result of a long combustion chamber and unburnt fuel making it to the exhaust. They also have problems with rotor sealing as a result of uneven temperat