At last week's Tokyo Motor Show, Mazda unveiled a new sports-car concept called the RX-Vision.
Beneath the car's sleek bodywork was what will likely be the first production Mazda rotary engine since the discontinuation of the RX-8 sports car back in 2012.
Called SkyActiv-R, it was unveiled with virtually no accompanying technical or production details.
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It was previously rumored that a new rotary engine could form part of an extended-range electric powertrain.
But electrification won't be in the cards initially, according to a report from CarsGuide.
"I want to introduce the new rotary without electrification first," Mazda R&D boss Kyoshi Fujiwara said in an interview at the Tokyo show.
He said re-launching the rotary as part of a hybrid or extended-range electric powertrain would lead people to think that "electrification helped the rotary engine."
Past rotary engines suffered from fuel-economy issues and other shortcomings, which has created some skepticism about their viability in a world of ever-tightening emissions standards.
The earliest Mazda rotary cars in the 1960s and 1970s had major durability issues with the engine seals at the tips of their rotors, which took years for Mazda to solve.
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Mazda's Fujiwara said the new SkyActiv-R rotary engine will launch with turbocharging.
While these comments would seem to indicate a change in the company's priorities, Mazda had previously experimented with a rotary range extender.
A tiny 330-cc rotary was installed in a Mazda 2 prototype back in 2012, and used to charge a battery pack that powered a 100-horsepower electric motor.
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The Audi A1 e-tron concept shown at the 2010 Geneva Motor Show used a similar setup.
But the debut of the RX-Vision concept indicates Mazda will use the SkyActiv-R engine in a sports car, at least initially.
There have been plenty of reports on a potential successor to the RX-8 and RX-7 sports cars over the years, including one of a possible hybrid model.
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Rumored to be called RX-9, a report last year claimed such a car could sit above a revived RX-7 in the Mazda lineup, but won't launch until 2020 at the earliest.
The rotary engine seemed full of promise in the early 1970s, but General Motors and other makers who planned to adopt them never did so--despite investing tens of millions of dollars into preparations to do so.
The plans were canceled due to the significantly inferior fuel efficiency of 1970s rotaries against conventional reciprocating engines of the same power.
If Mazda can turbocharge a new generation of rotaries and produce fuel economy that's at least on a par with its own conventional SkyActiv engines, it will have overcome a major stumbling block to wider use of the small, high-output design.