Mazda’s Confusing Plan to Resurrect the Famously Dirty Rotary Engine

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The Wankel rotary engine is a wonderfully visceral thing. It clatters and sings and produces an absurd amount of power for its size. But it’s also archaic, in the way old cars often are, which makes it odd to think Mazda wants to bring it back.

Rotaries are what made Mazda, in cars like the 1968 Sports Cosmo. The sleek two-seater I drove at Mazda’s top-secret Mine test track smelled of gasoline and weathered leather and wood. The houndstooth interior only added to the vintage vibe. No power steering, sticky drum brakes, a car so simple you could feel the mechanics in every action and hear the rotary engine rattling—not humming, mind you, rattling—loud up front. Next up was a 1984 RX-7 with no traction control. I nearly lost it on the first corner, the car’s tiny wheelbase allowing the wedge to spin like a bottle with the slightest prodding of the throttle. Then there came a second-gen RX-7, and an early 2000s RX-8.


Each packed a rotary engine. As the Mazda folks constantly reminded those of us driving the cars, this is something no other automaker could offer, because no other major automaker has mass-produced a rotary powered car. Not that they haven’t tried: Nissan, GM, Toyota, and Ford Germany threw some heavy investment into developing the challenging powertrain, but not one of them succeeded.

So why did Mazda invite a handful of journalists to its track to experience an anachronistic technology phased out three years ago due to its infamously low efficiency and high emissions? Because Mazda vows to resurrect the Wankel in the splashiest way possible. At the Tokyo Motor Show last month, it unveiled the stunning RX-Vision concept car, creating a social media cannonball.

As cool as its sounds, one can’t help but ask why? To understand, you must first understand the rotary engine’s incalculable importance to Mazda Motor Corp and its place in the company’s history—and how it could play an intriguing role in shaping the future.

Saving Mazda

In order to strengthen the country’s post-war economy, the Japanese government decided to consolidate 10 automotive brands into three companies. The idea was to eliminate competition and foster the development of shared resources. Hino, Isuzu, and Prince were to concentrate on trucks; Honda, Subaru, Daihatsu, and Suzuki would combine and focus on cars. Nissan, Toyota and Mazda would merge as well. Mazda president Tsuneji Matsuda figured the only way his small company could maintain independence was to bring a unique technology to the table. He turned to German engineer Felix Wankel’s rotary engine.

Mazda is placing its bets—and its future—on those same Dorito-shaped rotors.


A potentially revolutionary technology, the Wankel, or rotary, engine substituted the reciprocating pistons of a traditional internal combustion engine with triangular rotors that revolve in ellipses, converting combustion pressure into a rotating motion. Because they can run at very high revolutions, Wankel rotaries generate more power per liter than piston engines. The powerful, compact engine was a promising powerplant for an industry specializing in small cars for urban commuting.

On May 30, 1967, the two-rotor Cosmo Sport hit showrooms; an improved version followed a year later. Within a decade, Mazda’s sales grew tenfold, from 41,000 vehicles to 400,000. Its employee headcount ballooned from under 4,500 to over 21,000. The company sold more than one million RX-7 and RX-8 sports cars between 1978 and 2012.

The rotary engine is a fundamental part of Mazda’s history. You can’t sneak off to the bathroom at its Hiroshima plant without someone reminding you the rotary is a part of their DNA. Even locals have been indoctrinated; a guide at the train station said, “Aaah, rotary!” when I mentioned where I was going.

Because of this history, Mazda is placing its bets—and its future—on those Dorito-shaped rotors. But just because the rotary engine saved Mazda in the 20th century, will it have any chance to do so in this 21st? Mazda sure seems to think so.

The Problem

The last RX-8 rolled off the assembly line in 2012, its rotary engine forced into retirement by evermore-stringent global environmental regulations. (The company had long since embraced conventional engines in every other model, a process that started in the 1980s.) The advantages of rotaries are offset out by two big problems. A large combustion chamber means the engines burn a lot of fuel and produce a lot of CO2 emissions. The engines also produce relatively low torque, and aren’t known for great reliability. Torque and reliability are not insurmountable issues, but efficiency was another issue. The RX-8 delivered a paltry 19 mpg combined. Mazda tried mightily to fix the problem, but despite considerable investment the a 1.6-liter direct-injected engine shown in the 2007 Taiki concept never saw production. It couldn’t meet emissions expectations.

The automaker has money to spend on R&D—it notched a record profit of $1.41 billion in FY 2014. But it’s a small company and doesn’t have the luxury of funding a project that may not pay off. Trying to make the rotary work, instead of directing resources to improve its already excellent and fuel-efficient SkyActiv four-cylinder engines, could bury the company in its own history.

So the million-dollar question comes to the surface: how important is it for Mazda to develop a rotary powerplant? Is it really that imperative to the fundamental existence of the automaker?

“The fact is if you’re just looking at the numbers financially, then this investment we’re talking about is maybe not a correct investment,” says Mazda managing executive officer Kiyoshi Fujiwara.1 “However, there are two reasons that we still need to make an investment in this: the first reason is because we want to take really good care of our customers and fans, and another is for the satisfaction of our employees. For the morale of the colleagues we work together with here.”

The Hydrogen Solution

There is a path that makes more sense, one that neatly sidesteps the rotary’s key weaknesses: hydrogen.

In the auto industry, hydrogen typically is shorthand for fuel cells, which combine the element with oxygen to generate electricity without carbon emissions. But there’s another way to put the universe’s most abundant element to use: With relatively few modifications, you can make a rotary engine run on hydrogen. The drop in performance is almost imperceptible, and you get no carbon emissions.

Mazda has developed several working hydrogen rotary engines. The RX-8 Hydrogen RE, revealed at the 2003 Tokyo Motor Show, ran a dual-fuel rotary engine that could be powered by petrol or hydrogen, switching between them at the push of a button.

Then there was the Premacy Hydrogen RE Hybrid, which used the hydrogen rotary as a generator for an electric motor that turned the wheels. It brought a 40 percent increase in power, better acceleration, and twice the range of the RX-8 Hydrogen RE. That raises the possibility of using a rotary as a range extender, an internal combustion engine that provides energy to an EV when the battery runs out—a system used in the Chevrolet Volt. A battery-powered electric car, with a hydrogen-powered rotary to extend range, would be a DNA-loyal powerplant with a place in the zero emission, alternative energy future.

Even if you run it on gas instead of hydrogen, a rotary is better suited to being a range extender than a conventional engine. That’s because it’s especially efficient at low, constant engine speed (rpms)—which is exactly how a generator runs. Its compact size helps, too. Audi toyed with the idea in 2010 with the early A1 e-tron concept, using a tiny 250cc rotary to charge the battery. An electrified Mazda2 hatchback from the 2013 Tokyo show used a 330cc rotary to extend its range by 124 miles.


Yes, there are problems with hydrogen. The infrastructure for producing and distributing the fuel is nearly non-existent. Despite recent promises of heavy investment from the likes of Toyota and Honda, there simply are not enough fueling stations to make it a viable solution for John Q. Public. But things are happening. The governments of Japan and California are particularly dedicated to their development of the technology. Hydrogen-powered vehicles are finally hitting showrooms in both places. Hydrogen stations are being built, slowly but surely.

There’s a lot to be said for zigging when the rest of the world is zagging, for betting on yourself and your experience instead of chasing trends.

So why not make a hydrogen-powered rotary now, either as a primary or secondary powerplant? Turns out, Mazda’s doing just that. While I was driving the RX-8 Hydrogen RE, Mazda engineer Yasushi Fujikawa, riding shotgun, mentioned he leads a team of five engineers working full-time on a hydrogen rotary, though he revealed nothing about the precise form the powerplant was taking or how it could be used.

Fujiwara concedes Mazda is developing a hydrogen rotary, but not for cars, at least initially. Because hydrogen is a byproduct of its manufacturing process, Mazda is researching how it can re-use the element in a static rotary engine—meaning not in a mobile application, but in a fixed location, for example next to a plant as a standing generator.

“Now that kind of technology may come into play in the future if the infrastructure for hydrogen ever becomes viable,” Fujiwara says. “We can then utilize that technology to make a hydrogen range extender.”

Despite the rotary engine’s ample promise as a range extender, Fujiwara insists that is not how the engine will return. “I want to introduce a new rotary without electrification first,” he says. “If I introduce it with both, people will say electrification helped the rotary engine.”

So pride is clearly an issue. And there’s still no guarantee hydrogen will ever become a widely available fuel source, hence the old joke, hydrogen is the fuel of the future—and always will be.

A Very Vague Vision

Into this world the RX-Vision was born. Standing proudly on the dais at the Tokyo Motor Show last month, Mazda President and CEO Masamichi Kogai declared, “This car embodies Mazda’s vision for the future.” At once cleanly elegant and beautifully proportioned, the concept boasts a low-slung hood, razor thin LED headlamps, 20-inch wheels, and curves so polished they look like water-tumbled stones. Only a rotary could fit in an engine bay so short and tight.

It is a fantastical beauty, worthy of the hype it received. It is so fantastical, in fact, that Mazda design chief Ikuo Maeda says his team didn’t consider any real-world restrictions, like wheelbase or powertrain limitations, when they drew it up. In every way—the otherworldly sheet metal, a nebulous powertrain, questionable utility—the RX-Vision feels driven by fantasy. It is telling that it is the vehicle that embodies Mazda’s vision for the future, because you’ve got to wonder how much Mazda’s commitment to the rotary powerplant is grounded in reality.

There is no question, Mazda’s undying rebel spirit is utterly respectable. There’s a lot to be said for zigging when the rest of the world is zagging, for betting on yourself and your experience instead of chasing trends. But you wonder if dogged loyalty to its history will only ensure Mazda’s place in it.

1Post updated at 15:10 EST on December 1, 2015, to include comments from Mazda managing executive officer Kiyoshi Fujiwara.

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