Subaru Explains How Its New Hybrid Boxer Engine is Better

Some automakers are trying to save the manuals while others are attempting to rescue the internal combustion engine. Toyota, Mazda, and Subaru held a joint conference to explain how decarbonization can be achieved without going all-in on EVs. Toyota has three new smaller and more efficient engines in the works. Mazda is pursuing single- and two-rotor engines. Here's what Subaru is cooking up.

It has figured out how to keep its horizontally opposed engine alive in a next-generation hybrid system. During the conference, the company showed a prototype of its electrified boxer inside a camouflaged Crosstrek prototype. The outgoing setup relies on a parallel system where the engine and motor both power the vehicle. The new series-parallel layout will maintain a mechanical connection between the ICE and the wheels but the combustion engine will also serve as a generator to feed a battery that powers an electric motor.

Subaru argues the new hardware brings notable benefits not just in terms of fuel economy but also in packaging. The engine, hybrid system, transmission, and transfer case are all housed together while the power control unit is located in the engine bay, without negatively impacting the size of the fuel tank. That allows the engineers to install bigger gas tanks to achieve a longer range.

In the old Crosstrek hybrid, the power control unit was mounted at the rear, so the fuel tank had to be downsized to make room for it. Thanks to the new arrangement, Subaru claims the fuel tank's size will be almost the same in the hybrid as in the regular gas-only model. Chief Technology Officer Tetsuo Fujinuki touts a "very long cruising distance." During his speech, he said the new system must solve the "current weakness in fuel efficiency."

The company's CTO admits that if fuel economy is the ultimate goal, the boxer engine might not represent the ideal solution:

"If you were just going for efficiency, horizontally opposed engines are not necessarily always the best option. But what would Subaru be without them? When you think about it, we are the only mass-market brand making horizontally opposed engines today."
Toyota also uses a boxer engine but only in the GR86 sports car, which is a sister model of the Subaru BRZ. Porsche has flat-four and flat-six engines but it's far from being a mainstream brand given how much their cars cost.

Subaru plans to start production of its next-gen hybrid boxer engine this fall at a factory in Kitamoto, Saitama at home in Japan. As you can imagine, the hardware is being conceived for all-wheel-drive applications.

In related news, the company is working together with Toyota and Mazda on carbon-neutral fuels. To that end, it'll enter a WRX-based High Performance X Future Concept in the Super Taikyu racing series.

Since we mentioned Mazda earlier, the Zoom-Zoom company is doing things differently with the revival of its rotary. In the MX-30 small crossover, the engine doesn't actually send power to the wheels. Instead, the sole purpose of the transversely mounted rotary is to act as a generator to juice up a battery. An electric motor uses the harvested energy to drive the wheels.

Mazda is already working on a different layout for a longitudinally mounted two-rotor engine that could go into a new sports car, potentially an RX7 reboot it's "considering."