Published on October 23rd, 2024 | by Subhash Nair
0Subaru Unveils Advanced Series-Parallel Hybrid Powertrain with 1,000km Range
The next-generation Subaru hybrid powertrain will improve on all aspects.
Subaru don’t sell their hybrid models here, but in many other markets, they’re pretty popular. That being said, I’ve heard anecdotally that their current hybrid powertrain isn’t particularly frugal and barely offsets the inefficiencies caused by the weight added to the system. We’re sure Subaru have known about this for years, which is why they’ve been quietly working on a much improved version with a larger displacement engine, a more powerful electric motor and a larger battery pack. It will be coming to Japan’s third-gen XV, known exclusively as the Crosstrek now. This model is not sold in Malaysia, as we’re still on the second generation XV here.
The centerpiece of Subaru’s next-generation hybrid system is a purpose-built 2.5-liter horizontally-opposed boxer engine, working in concert with a sophisticated dual-motor hybrid transaxle. This series-parallel system intelligently switches between pure electric and combustion power depending on driving conditions.
The newly developed transaxle houses two electric motors – a high-output 88kW traction motor and a dedicated motor-generator – alongside the front differential gear and electronically controlled coupling in a single unified package. This integrated design allows the traction motor to serve as the primary power source in many driving scenarios, with the Boxer engine providing supplementary power when needed or taking over in conditions where electric drive is less efficient. While the press release does not specifically mention this, it has been suggested that some electrical components in this hybrid powertrain are derived from Toyota.
Subaru’s engineers have maximized the packaging advantages of the flat-four engine layout, enabling the integration of both a larger high-voltage battery and an expanded 63-liter fuel tank. The power control unit has been relocated from beneath the cargo floor to above the engine, freeing up space for these larger energy storage components. Combined with a roughly 20% improvement in fuel efficiency over the previous hybrid system, this larger fuel capacity enables a breakthrough 1,000-kilometer driving range on a single tank – the longest range of any Subaru vehicle to date.
The high-voltage lithium-ion battery pack, featuring advances in energy density and weight reduction, is positioned under the cargo floor to maintain a low center of gravity. This new battery technology also boasts enhanced longevity compared to previous generations.
Staying true to Subaru’s all-wheel-drive heritage, the system retains a mechanical AWD setup with the front and rear wheels coupled through a traditional propeller shaft. This arrangement ensures precise torque distribution and maintains Subaru’s characteristic all-weather capability and off-road performance.
The new Boxer engine itself has been specifically engineered for hybrid duty, featuring improved thermal efficiency for better fuel economy while maintaining strong dynamic performance. An integrated power control unit mounted atop the engine manages the power flow from the high-voltage battery, optimizing overall electrical efficiency.
The comprehensive system redesign has also yielded improvements in NVH (Noise, Vibration, and Harshness) characteristics, particularly during electric-only operation. The upgraded electric drive capabilities allow for more extensive EV-mode operation, contributing to both the improved efficiency and quieter operation.
This next-generation hybrid system will make its debut in the Japanese-market Crosstrek in December 2024, representing Subaru’s most advanced electrified powertrain to date.