The Subaru B5-TPH is a stylish coupe/wagon/crossover concept that Subaru stresses is not the next Impreza. Its main focus is not the exterior styling so much as Subaru’s Turbo Parallel Hybrid (TPH) powertrain, which is linked to the company’s trademark symmetrical four-wheel-drive system. That’s a shame, since the B5-TPH is the best-looking vehicle to come out of Subaru’s studios in some time.
TPH places a thin electric motor generator between the car’s 2.0-liter Miller-cycle flat-four turbo engine and the automatic transmission. The Miller-cycle technology, which we last saw in the mid-1990s Mazda Millenia near-luxury sedan, improves engine efficiency by reducing pumping losses due to a power stroke that is longer than the compression stroke. Often, this system makes an engine unresponsive at low speeds, but with the electric motor, Subaru claims, standing-start torque is better than even the turbocharged Impreza WRX’s. The generator also acts as an engine-assist to boost fuel economy. The combined output is 256 hp and 253 lb-ft of torque.
Subaru says while there are no plans to build a car that looks like the B5-TPH (which sits on a modified Legacy platform), some variation of TPH is likely for production, maybe in the Legacy or Forester, by 2007.