If ever there was an automotive brand that embodied the spirit of hybrid cars—urban, progressive, outdoorsy, family-oriented—it would be Subaru. Furthermore, Toyota, the hybrid leader, owns 16 percent of Fuji Heavy Industries, the maker of Subaru cars. Yet, loyal Subaru owners continue to wait in vain for the Japanese company, whose name translates to “unite,” to delivers on its promise to go hybrid.

In May 2009, Subaru announced plans to introduce a gas-electric hybrid car by 2012—but provided no details. Readers of this website responded with enthusiasm. Family Guy wrote, “I want it. My 2002 Outback will be 10 years old by 2012. Now, I can look forward to the possibility of replacing my Subaru with a hybrid from Subaru. Woo!” But others appeared tired of waiting. TS wrote, “We leased a 2005 Outback, hoping they’d have a hybrid by the time the lease was up. Didn’t happen. Too bad. Bought a Prius now. They missed a window.” William admonished Subaru, “Toe dipping in the hybrid pool is useless.”

Subaru continues to dip its toes—and retreat. A few years ago, the company unveiled the Subaru B5 TPH (for Turbo Parallel Hybrid) concept car—a sporty two-seat, all-wheel-drive grand tourer that blends elements of a coupe, sporty hatchback, and Outback sport-utility. The company has been testing its diminutive Subaru R1e all-electric two-seat city car in the US—and in August even managed to launch the R1e-derived Subaru Stella Plug-In in Japan. The tiny Stella employs a 9.2 kilowatt-hour, 346-volt lithium ion battery pack and 47-kilowatt motor to deliver a top speed of 60 mph and a driving range of about 50 miles. Unfortunately, the car sells for $48,000—minus Japanese government incentives of nearly $20,000. (Mitsubishi offers the all-electric i-MiEV at a similar price.) Subaru is producing merely 170 units of the Stella Plug-in, essentially a small test run.

In the current run up to the 2009 Tokyo Motor Show approaches, some hybrid fans harbored hope that Subaru would finally pull the wraps off a practical affordable Subaru model heading to a US showroom sometime soon. Instead, the company yesterday announced plans to present the four-seat Subaru Hybrid Tourer Concept, yet another hypothetical rad-cool vehicle with gull-wing doors, lithium ion batteries, and motor-generators in front and back to electrify the company’s signature all-wheel drive and direct fuel-injected Boxer engine.

Subaru Hybrid Tourer Concept

The Subaru Hybrid Tourer Concept, like the company’s previous concepts and hybrid announcements, will whet the appetite of eco-conscious Subie fans. At the same time, it will leave many of them wondering if Subaru will ever deliver a super-efficient ultra-safe gas-electric hybrid.

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It stands to reason, then, that a Subaru hybrid would be slightly different. The Subaru B5 TPH (for Turbo Parallel Hybrid) concept, a sporty two-seat, all-wheel-drive grand tourer, blends elements of coupe, sporty hatchback, and Outback sport-utility. Its turbocharged 2.0-liter boxer four develops 191 kW (256 hp) and 253 foot-pounds of torque. The company’s engineers added a very thin—just 58 mm—electric motor-generator between engine and transmission. Though it produces just 10 kW (13 hp) at peak power, it pulls like a steam engine, generating 110 foot-pounds of torque from start-up.

This neatly offsets the characteristic “turbo lag” —in which turbochargers provide little power until they have spooled up to full operating speed. The hybrid also compensates for the characteristics of the Miller cycle engine (defined as the Atkinson cycle used in all hybrids plus forced induction from a turbo- or super-charger). What’s the Atkinson cycle? It’s a variation on the standard Otto cycle gasoline engine, in which valve timing simulates a cycle in which the piston moves through strokes of different lengths. This extracts more energy from the fuel because on the power stroke, the combusting air-fuel mixture can expand to a greater volume than it originally occupied on the intake stroke…but low-speed power is terrible, so the hybrid’s low-speed torque fits nicely.

Unlike full hybrids that can run on batteries alone, both power sources—engine and electric motor—operate full time. This let Subaru fit a much smaller and more compact motor, adding just 200 lbs (100 kg) of weight including the battery pack.

A crucial component of the B5-TPH is its manganese lithium ion batteries, co-developed by Fuji Heavy Industries (Subaru’s parent) and NEC Corp. With 50 percent greater power density than the Nickel-Metal-Hydride batteries in hybrids today, Li-ion batteries also offer much faster recharge. The weak spots of Li-ion batteries have traditionally been their life cycle, which varied with use cycles rather than time, and their heat generation. Subaru and NEC claim to have solved these problems, though the company has released very few details. Experimental numbers of the TPH powertrain will appear first during 2007 in versions of the Legacy sedan, in Japan only.

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