Mazda's new patent describes an exhaust gas recirculation (EGR) system specifically adapted to the characteristics of a rotary engine. Emission problems were one of the reasons why RX-8 production ended in 2012.

The design uses two different rotor exhaust lines. The hotter flow from the side port is directed to the turbocharger, while the cooler flow from the peripheral port passes through an integrated channel to the EGR cooler. This uses the engine's standard cooling system, eliminating the need for some external piping.

Under high load, when gas recirculation is not required, the cooled flow is proposed to be directed to a second catalytic converter. This scheme should help control exhaust composition more effectively without significantly complicating the compact Wankel.

This is especially important for Mazda. The company is already working on rotary technologies and has previously shown the Iconic SP and the Vision X-Coupe concept. At the same time, a modern rotary engine has already returned in the MX-30 R-EV, but there it served exclusively as a generator for recharging the battery.

The new patent is notable because it potentially solves a problem for another scenario – a rotary engine that directly participates in the powertrain's operation. However, the patent itself does not mean preparation for a production car: Mazda has not yet linked this development to a specific model.

But the coincidence looks too curious: the company continues to look for a way to make the Wankel compatible with modern environmental requirements, which means the story of the RX-7 and RX-8 is not necessarily over yet.