Sources at Subaru have told just-auto that the company has decided - contrary to expectations - not to buy-in Toyota's full hybrid HSD system for future Subaru hybrid models, but to develop its own mild hybrid system instead.

In 2005, when Toyota purchased the 8.7% share of Fuji Heavy Industries sold by General Motors, it was widely expected that FHI would benefit not only from Toyota’s manufacturing expertise but also its experience and production base for hybrid components. While Subaru had shown a number of hybrid concepts over the years – all incorporating the company’s characteristic boxer engines and all-wheel-drive system – it was not clear that it had serious plans to put them into production.

Now, a Subaru executive who spoke to just-auto in September 2011 on condition of anonymity has confirmed that the company will launch a hybrid model in Japan in 2013 - as indicated in Subaru's "Motion-V" strategic plan for 2011 to 2015.  But, that executive said, contrary to expectations, Subaru's hybrid will not utilize the Toyota Hybrid Synergy Drive (HSD) system mated to an existing Subaru boxer engine. Instead, Subaru's stubbornly independent engineers have created a Honda-style mild hybrid, without the ability to run solely on electric power at low speeds.

Like other mild hybrids, notably the General Motors "eAssist" add-on, the Subaru installation uses a low-power electric motor to restart the engine when the car moves way from a stop, to add supplemental torque to the engine output, and to recharge a small battery pack of less than 1kWh via regenerative braking.

The Subaru Hybrid Tourer concept unveiled at the 2009 Tokyo Motor Show used a 10kW electric motor between the turbocharged 2.0-liter flat-four engine and the Lineartronic continuously-variable transmission, in a preview of the production system. Its lithium-ion battery pack is derived from the one used in the Stella EV minicar. (The Hybrid Tourer concept also used a 20kW electric motor powering the rear axle, giving it all-electric running under some circumstances, but that is unlikely to appear in the company's first production hybrid.)

Reports indicate that the hybrid model launched in Japan will be a version of the Legacy D-segment four-door saloon (known as Liberty in Australia). But the Subaru executive who spoke to just-auto said Subaru of America had not yet decided which model should launch the hybrid in the U.S. (which is the world’s largest hybrid market).

Candidates for the North American hybrid launch include the 2014 Legacy Hybrid, the popular D-segment Outback estate crossover, or the C-segment Forester softroader. Subaru has an enviable green reputation in the States, and its owner base is psychographically the most progressive of any marque sold in the States, so a hybrid Subaru seems a natural fit. Indeed, the executive said, dealers have been clamouring for one for years.

Schedules have slipped, however. Subaru had been expected to unveil its first hybrid during 2011, with sales starting late that year as a 2012 model. More recent reports in March 2011 placed that introduction as far away as 2013, making the car a 2014 model. The company's 'Motion-V' business plan, released in July 2011, also said the hybrid Subaru is "planned for 2013," and that date now seems firm.

The research for this article was undertaken as part of just-auto's QUBE research coverage. For more news and insights on mild- and full-hybrids as well as electric vehicles and associated technologies, see just-auto's QUBE research platform.