A newly filed emissions-control patent could help Mazda make turbocharged rotary engines more practical for future performance cars.
Mazda has filed a new patent for a compact exhaust gas recirculation (EGR) system designed for turbocharged rotary engines, reigniting speculation that the Japanese automaker could eventually return to the sports car segment with a rotary-powered model.
The patent was filed with the United States Patent and Trademark Office earlier this year and details an emissions-control system specifically adapted for a Wankel rotary engine. The technology appears aimed at reducing harmful nitrogen oxide (NOx) emissions while also supporting improved engine performance.
New EGR System Targets Rotary Engine Emissions
According to the patent, most of the engine’s exhaust gases would exit through the side port, while a significantly smaller quantity would leave through the peripheral port. Mazda proposes directing the hotter side-port exhaust toward a turbocharger to help increase engine power and torque.
Meanwhile, the cooler exhaust produced through the peripheral port would pass through a compact cooling system before being redirected into the engine. This recycled exhaust could help reduce combustion temperatures and lower NOx emissions.
The approach could also provide packaging benefits. Conventional EGR systems generally require relatively large cooling hardware because substantial amounts of hot exhaust need to be cooled. Mazda’s proposal reduces this requirement by using the cooler peripheral-port exhaust, allowing the EGR components to remain close to the engine.
When EGR operation is unnecessary, the exhaust would instead be routed directly toward the vehicle’s second catalytic converter.
Patent Fuels RX Sports Car Speculation
While the patent does not confirm that Mazda is developing a production sports car, the inclusion of a turbocharger is particularly interesting. It suggests the proposed rotary could potentially be used in a vehicle where the engine contributes directly to driving the wheels rather than functioning solely as a range extender.
Mazda’s last rotary-powered model with the engine driving the wheels was the RX-8, which ended production in 2012. Its naturally aspirated 1.3-litre twin-rotor engine produced outputs ranging from 143kW and 198Nm to 173kW and 216Nm, depending on specification.
The company later revived rotary technology in the MX-30 R-EV, although its 830cc rotary engine was used exclusively as a generator to recharge the SUV’s battery.
Mazda Continues Rotary Development
Mazda has continued to keep interest in rotary technology alive through concept vehicles. The 2023 Iconic SP showcased a sleek two-door sports car featuring a twin-rotor range-extender system, while the 2025 Vision X-Coupe concept featured a turbocharged twin-rotor engine within a 375kW plug-in hybrid drivetrain.
The latest patent does not guarantee that either concept will become a production model. However, it demonstrates that Mazda continues to investigate ways of making rotary engines cleaner and more efficient, potentially keeping the door open for a future performance-focused rotary vehicle.