A new Mazda rotary patent suggests the automaker is still working to overcome the emissions challenges that have kept its Wankel engine from making a full production comeback. The proposed system would use the rotary engine’s existing exhaust characteristics to create a form of internal exhaust gas recirculation (EGR) without relying on the external tubing used by conventional systems.
Why Mazda Moved Away From Its Rotary Engine
Mazda’s rotary engines have relied almost entirely on internal EGR rather than external EGR since the technology debuted in 1967. The approach was possible because of the way the Wankel design handles combustion.
That workaround eventually became insufficient as emissions regulations tightened. Mazda ended production of the RX-8’s rotary engine in 2012, leaving the company’s rotary ambitions limited to concept vehicles and a range-extender role in the now-discontinued MX-30 R-EV.
The new filing indicates that Mazda engineers are continuing to explore ways to overcome those emissions challenges for a potential production rotary.
How Mazda’s New EGR System Would Work
The patent, filed with the US Patent and Trademark Office (USPTO), describes dividing the rotary housing’s two exhaust routes so they can serve different purposes.
The higher-volume, higher-temperature side-port exhaust would be directed to a turbocharger. Meanwhile, the cooler peripheral-port exhaust would travel through an internal passage to an EGR cooler that uses the engine’s own coolant system.
That arrangement would avoid the external tubing required by a conventional EGR system. Under heavy load, when EGR is not needed, the cooled exhaust gas would instead be sent to a secondary catalytic converter rather than the first converter.
What the Patent Could Mean for Mazda’s Rotary Plans
The filing does not confirm that Mazda has a production plan for the system, and the automaker has not connected the technology to any specific model.
However, the patent arrives alongside two rotary-powered concepts Mazda has teased in recent patent filings: the Iconic SP and last year’s turbocharged Vision X-Coupe. Both face the same emissions challenge that the new patent is designed to address.
Mazda has been candid about the difficulty of balancing those requirements, emphasizing that any production rotary sports car would also need to remain commercially viable and affordable.
Mazda Continues to Explore the Rotary
It remains unclear whether this specific EGR design will eventually be used in the Iconic SP, a future RX successor or no production vehicle at all. The patent nevertheless shows that Mazda continues to work on the technical challenge surrounding the rotary engine and its potential return to production.
