Toyota, Mazda, Subaru Agree Carbon Is ‘Enemy' with Internal Combustion Engine Announcement

July 31, 2024

Sebastian Blanco

Toyota, Mazda and Subaru announced a new technological effort to create new internal combustion engines and ways to use them in the electrification era, specifically for hybrid and plug-in hybrid vehicles. The companies said at a joint press conference in Japan that they would encourage increased use of petroleum alternatives like biofuels and eFuels in their effort to create carbon-neutral vehicles. A joint statement from the three OEMs claims this push for new and better ICEs comes with a focus on “carbon as the enemy” as they develop engines that can better work with electric motors, batteries, and other electric drive units. Toyota, Mazda and Subaru made clear they are not getting rid of EV-only vehicle plans.

Here’s how each company will approach the new ICE+EV era (quotes provided in English by on-site interpreters).

Toyota: smaller, better engines

Toyota will develop new, low-displacement inline four-cylinder engines, Toyota president and CEO Koji Sato said, with an emphasis on increased efficiency and more compactness by combining the engine with an electric power unit.

“Based on the concept of adding an engine onto an electric unit, we are refining our technology to achieve higher efficiency than before by leveraging the areas in which each electric motor and engine excel,” Sato said. “By optimizing engines for electrification, we will make their structure more competitive and compact, which will lead to more flexibility in engine installations in cars.”

Toyota’s chief technology officer, Hiroki Nakajima, said that the company’s new, naturally aspirated 1.5-L engine would be 10% smaller in both volume and height, while offering better fuel economy and around the same power output. The new 1.5-L turbo engine would be similarly smaller (a 20% volume reduction and a 15% height reduction) compared to the current 2.5-naturally aspirated engine and will trade slightly worst fuel-efficiency for a 30% improvement in horsepower. Finally, Toyota’s new 2.0-L engine will, compared to the current 2.4-L turbo, be 10% smaller and shorter, with better efficiency and, again, around 30% higher hp.

Mazda: rotary to the future

Mazda is looking to the past when it comes to finding the correct future for ICEs by considering using the rotary engine for the new HEVs and PHEVs.

“From an early stage, we have explored the environmentally friendly potential of these engines, including burning hydrogen in the 1990s,” Mazda president and CEO Masahiro Moro said during the press conference. “Rotary engines are compact and lightweight, and yet have a high output. The structural characteristics make them omnivores with respect to fuels. What's more, though not widely known, their compact size and relative freedom in the layout of auxiliary parts allow for high space efficiency and easy mounting of electric devices, offering a great advantage for innovative packaging and design.”

Moro said the inherent benefits of a rotary engine, specifically the quietness and low vibration, give it a "singular value.”

"We believe that the rotary engine holds great potential for providing new value in the age of electrification and we are devoting all our energies to overcoming the current challenge of emission compliance for our rotary engines,” he said.

Subaru: EVs with AWD will keep the “Subaru difference”

Subaru is not giving up on the Boxer engine. New ICE-plus-electric powertrains from the company will keep the brand’s symmetrical all-wheel drive layout for future hybrid and PHEV models, but Subaru president and CEO Atsushi Osaki said his company remains open to all different kinds of powertrain options.

“At Subaru, we are navigating this period of a great transformation by focusing on flexibility and expandability,” he said. “At Subaru, internal combustion engines mean horizontally opposed engines. The company's pioneers regard longitudinally mounted, horizontally opposed engines as the logical and ideal source of power for automobiles. This has developed into Subaru’s unique symmetrical AWD system with a superior packaging that takes advantage of a symmetrical powertrain layout and the features of a horizontally opposed engine: lightweight, compact, low center with gravity reduced vibration and the safety in collisions.”

Subaru’s new powertrain layout, still with AWD, will be a series-parallel system that uses an ICE that will either directly power the wheels or send power to a generator, which will in turn power a batter that moves the motor and then the wheels. The car will decide where to send ICE energy by choosing the most-efficient path.

Subaru’s future hybrid and PHEV models will likely have fuel tanks that are the same size as a gasoline-only car, Subaru said, but it won’t need to be filled with a petroleum product. “Subaru is also eager to collaborate in efforts to promote the adoption of a carbon neutral,” Osaki said. "The challenge of creating a carbon neutral society needs to be tackled and not just by the three companies here, but by all of the Japanese industry and society.”

Subaru said it will start producing transaxles for the next-generation hybrid system in the fall of 2024 at its Kitamoto Plant in Saitama Prefecture, Japan.

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