There have been rumors of Mazda reviving the rotary engine on a regular basis since the RX-8 ended production in 2012. The company itself has been pretty quiet about the rotary engine, except as a planned range extender in an upcoming plug-in hybrid version of the MX-30. However, Mazda has filed a patent application for a triple-rotor hybrid powertrain. And unlike in the MX-30, it not only appears to be the main propulsion unit, but it's also configured for a rear-wheel-drive layout.
The patent was filed with the European Patent Office, according to Japanese blogger taku2-4885. One of the detailed diagrams clearly depicts a rotary engine with three housings, similar in architecture to the triple-rotor found in the Japan-market Eunos Cosmo of the early 1990s. The rotary engine is connected to a 48-volt mild-hybrid assist system and a rear transaxle, similar to a Japanese patent for an RX-Vision-like coupe discovered back in August. There's also a description of a cooling system, something the hot-running rotary engine needs to maintain a long life.
Unlike those Japanese patent filings, these illustrations aren't nearly as detailed. They are likely a placeholder for something that Mazda might, one day, if market forces and planets are aligned, want to do. Of course, the gulf between that and a production car is incredibly wide.
And given the way market winds are blowing, it seems increasingly unlikely that a new combustion engine, especially using a design known for its thirst and emissions, will make it to production. Mazda has to worry about increasingly stringent rules for electrification and emissions, especially in Europe, to simply continue to sell cars in those markets in the future. It wouldn't be cheap not just to develop, but for people to buy.
We wouldn't say it's a completely hopeless case, either. Mazda hasn't given up on the rotary, evidenced by the range-extender plans. Also, if the Toyota partnership bears some electric fruit that allows Mazda to survive, we could see slim chance for a PHEV variant of this car existing. In all-electric mode, it would still be allowed in European city centers that have banned petrol engines altogether. It would definitely need something more potent than just a 48-volt electric motor to be a plug-in hybrid though.
There are countless other factors working against a triple-rotor RWD performance car, but we love the fact that Mazda, ever the dreamer, is even contemplating something like this.