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Mazda’s famous rotary engines could return to give electric cars much-needed range

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Mazda shows time-tested technology can be repurposed to complement new, state-of-the-art features like electric drivetrains.

The rotary engine tested by many and made famous by Mazda might be on the verge of entering a new chapter in its life. Patent filings and industry gossip suggest the Wankel will soon make a triumphant return as a compact range extender in a plug-in hybrid car.

On paper, the rotary engine would perform the same function as the 600cc two-cylinder available at an extra cost on the BMW i3. It wouldn’t directly drive the wheels, but it would generate enough electricity to charge the battery pack on-the-go. An electric car equipped with a gasoline-burning range extender inevitably emits a little bit of CO2, but it’s able to drive much further on a single charge.

A few drawbacks have prevented the Wankel engine from truly rivaling the piston engine. Notably, it uses more fuel and it typically produces less torque than a comparable four-cylinder. But, its advantages are well-suited to range-extending duties. It’s compact, which clears up more space for passengers, cargo, and in this application batteries, it’s light, quiet, and vibration-free. Mazda is even developing an advanced start-stop system to keep fuel economy in check, according to patent applications uncovered by Autoblog.

Mazda experimented with using a rotary engine in an electric car four years ago when it introduced the experimental Mazda2 RE concept. It never reached production, but engineers are using the data gathered over the course of the project to develop a series-produced electric vehicle tentatively scheduled to arrive in 2019.

While it sounds like Mazda isn’t giving up on the Wankel engine altogether, the prospects of seeing another rotary-powered, high-horsepower sports car in the foreseeable future are bleak. The company teased us two years ago in Tokyo when it debuted the RX Vision concept (pictured), which illustrated what form the next installment in the RX series could take, but CEO Masamichi Kogai bluntly replied “no” when asked if we’d soon see a new sports car positioned above the Miata.