Subaru to bypass Toyota’s Hybrid Synergy Drive and go with a mild hybrid instead

Just over 6 years ago, when General Motors sold an initial 8.7% stake in Subaru to Toyota, some pundits cited Subaru’s collaboration with Japanese information technology, electronic devices and semiconductor giant NEC on lithium-ion hybrid gasoline-electric batteries as one of the reasons for Toyota’s interest in Subaru. Yet, apart from a string of hybrid concept cars and a brief run of Stella (battery, non-hybrid) Electric kei microcars for the Japanese Domestic Market, nothing came of Subaru’s hybrid production plans. This past July, however, Subaru parent Fuji Heavy Industries’ “Motion-V” Mid-Term Management Plan for Fiscal Year 2012-2016 made a passing mention of a hybrid car to go on sale in 2013.

With Toyota’s stake in Subaru now doubled to 16.7%, and Toyota having licensed its hybrid technology to rivals Nissan and Mazda, there was widespread expectation that Subaru might follow suit for its first-ever production hybrid. Yet, in a surprising development, Dave Leggett of the subscriber-only just-auto site, reports that Subaru swerves Toyota HSD and opts to go it alone on hybrid tech. Indeed, it seems that Subaru has opted instead for a mild hybrid system reminiscent of Honda’s Integrated Motor Assist (IMA) and, to a lesser extent, General Motors’ current eAssist. Such systems lack the ability of Toyota’s Hybrid Synergy Drive to run solely on electric power at low speeds. Instead, their hybrid functionality is limited to restarting the engine when the car moves way from a stop via a low-power electric motor, adding supplemental torque to the engine output, and recharging the small battery pack of less than 1kWh via regenerative braking.

Just-auto further reports that the first Subaru hybrid will be a Japanese Domestic Market version of the Subaru Legacy sedan to debut during the 2013 calendar year as a 2014 model. This would be a variant of an all-new 6th-generation Legacy sedan if Subaru follows the pattern set by the 3rd-generation naturally-aspirated Impreza line and puts the current Legacy on a 4-year production cycle. For North America, however, Leggett claims that plans are less clear-cut, with not only the Legacy but its station-wagon Outback offshoot and the 4th-generation of the smaller Forester SUV all possible candidates for hybridization.

But why didn’t Subaru just go with the generally more fuel-economical Toyota hybrid system? John Voelcker of Green Car Reports suggests that

Subaru is a stubbornly independent company with a strong engineering culture. Aside from Porsche, it’s the sole company offering horizontally opposed engines, which are smaller and give vehicles a lower center of gravity than inline engines.

Fitting Toyota’s hybrid to a pancake engine might have posed its own challenges, but Subaru’s engineers developed their hybrid system internally, along with the lithium-ion battery pack. And so the Subaru hybrid that will launch as a 2014 model will be a mild hybrid–a technology that Toyota doesn’t offer.

Well, make that a technology that Toyota doesn’t currently offer. About 10 years ago, Toyota sold in Japan a mild hybrid version of the 11th-generation (S170) Crown Royal powered by a 3.0 liter 2JZ-FSE inline-6.

Illustration: Schematic of Subaru hybrid system as employed in 2009’s Hybrid Tourer Concept.

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