Idled for 11 years, Mazda Motor Corp.'s famed rotary engine is set to roar back to life this spring, this time helping to power a plug-in hybrid vehicle. 

The rotary engine, which Mazda was the first in the world to commercialize, disappeared temporarily from the automaker’s lineup because of its fuel inefficiency.

But the automaker is reviving it this spring for a hybrid vehicle model that will first go on sale in Europe. 

Company officials are hoping the rotary engine will have a new role to play in the coming age of electrification.

Mazda ended production of the RX-8 sports car, its last commercial vehicle model equipped with a rotary engine, in 2012.

The automaker is adding a rotary engine to the MX-30, Mazda’s first mass-produced electric vehicle model released in 2020. The addition will turn it into a plug-in hybrid vehicle, rechargeable from an external source, and put it on sale, for starters, in Europe.

There is a rapid shift toward electric vehicles in Europe, but the trend is facing its own challenges, such as the limited driving ranges of electric vehicles and the dearth of charging facilities for them.

The Mazda officials are hoping the plug-in hybrid with an engine could lure customers who are hesitating to buy an electric vehicle.

“The rotary engine, which is a part of Mazda’s heritage and a symbol of its challenger spirit, is finally coming back as a power generator for this new age of electrification,” said Wakako Uefuji, a Mazda program manager, during the Brussels Motor Show in January, where the automaker first unveiled a car of the plug-in hybrid model.

BANKING ON ROTARY ENGINE'S STRENGTHS 

A rotary engine uses rotational movement of triangular rotors to turn the wheels, as opposed to a conventional engine, which converts piston movement into rotary movement of the wheels. The rotary engine has the advantages of producing less vibration and having fewer component parts.

It is more compact, weighs less and has a higher output than a conventional engine. The rotary engine also has a higher degree of freedom of layout in a vehicle body.

Mazda officials decided that these strong points of the rotary engine will prove their worth in a plug-in hybrid, as the shift toward electric vehicles is still in a transitional stage.

The new plug-in hybrid has a maximum range of 85 kilometers on its battery alone. It will also carry a newly developed rotary engine, with a displacement of 830cc, and a 50-liter gasoline tank.

When its battery level gets low, it will rely on the gas-powered rotary engine to produce electricity and keep the motor running.

Mazda workers improved the fuel efficiency of the engine, which has long presented a challenge, by, for example, reviewing the composition of its parts and having the rotary engine continue operating in a revolution range that ensures higher efficiency.

A ride in the car feels much like riding in an electric vehicle.

Calculations show that the MX-30 plug-in hybrid has a total driving range of more than 650 km, although Mazda has yet to release an exact figure.

That will be about 400 km farther than the corresponding figure for the MX-30 electric vehicle model, which means there are fewer concerns about the battery charge running out while the car is on the move.

The plug-in hybrid will be marketed at prices that start at 35,990 euros (5.2 million yen, or $39,000) in Germany, the same as the starting price of the electric vehicle model.

The MX-30 plug-in hybrid will also be put on sale in Japan, but Mazda officials have yet to say when and at what prices it will be marketed there.

Mazda has continued with research and development of rotary engines even after the company stopped producing rotary engine cars 11 years ago.

Workers continue to manufacture rotary engines and their parts at a Mazda plant in Hiroshima Prefecture, the seat of the automaker’s head office. Mazda is making the most of that know-how in developing the new plug-in hybrid.

Global trends and environmental regulations, however, are pushing a shift toward electric vehicles, which emit no carbon dioxide while on the move. That is bad news for fans of internal combustion engines.

The chances are slim that a car model that runs solely on a rotary engine will ever roll off the assembly line again. 

One senior Mazda official previously said he didn’t wish to see another vehicle model forced out of production because of the difficulty in complying with new regulations.

‘HAPPY THAT ROTARY ENGINE REMAINS ALIVE’

Senji Hoshino, a self-employed mechanic of rotary engine and other vehicles based in Maebashi, the capital of Gunma Prefecture, owns a Cosmo Sport model, the world’s first mass-produced rotary engine vehicle, which Mazda rolled out in 1967.

Hoshino, 62, said he is fascinated by the feel of a rotary engine-powered vehicle, which increases its acceleration with every step on the gas pedal.

“It feels like an electric vehicle in the way it runs,” he said of the rotary engine vehicle being revived. “Still, I am so happy that the rotary engine has been kept alive.”

Mazda previously tried to lease rotary engine vehicles that can be fueled by hydrogen. And the auto industry has increasingly been working with the energy industry to conduct research and development of carbon-free fuels that can be used in engine vehicles.

“Technology does evolve,” Hoshino said in referring to similar moves. “I hope vehicles powered by rotary engines will make a comeback in the future.”

Mazda produced a total of 1.99 million rotary engine vehicles between 1967 and 2012.

(This article was written by Shiro Matsuda and Kohei Kondo.)