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Motor Show: Subaru B5-TPH


Forum Addict
Sep 7, 2004
Bradford, UK

B5-TPH is a crossover-style family wagon with Subaru's new hybrid system, which combines an electric motor and the Subaru flat-four 2.0-litre petrol engine, running on the Miller cycle.

In the Miller cycle, the intake valves stay open at the beginning of the compression stroke. Engines are usually 10-15% more efficient than conventional Otto cycle engines, as they require less energy to overcome friction and take a shorter compression stroke, but there has typically been a loss of power and low-down torque. In this Subaru prototype, this is compensated for by the addition of a turbocharger and the electric motor - the latter, giving 10kW, can add up to 110lb-ft of extra torque. The system also allows for a more compact motor and smaller battery than Subaru's earlier sequential-series hybrids, and is better-suited to the layout of the "boxer" engines.

The first production model to feature this so-called Turbo Parallel Hybrid (TPH) system will be the Legacy Hybrid, due 2007, and Subaru claims that in this car, it will produce around 255bhp yet return over 38mpg. However, the B5-TPH suggests that a hybrid new-generation Impreza wagon isn't too far behind.
Neat, good thinking on the way the engine functions. It keeps with the new look for Subaru, not many like it, but I certainly do.


(from Subaru Press Release) Symmetrical all-wheel drive specialist, Subaru, is to display a high-powered concept car at the ?39th Tokyo Motor Show? which is also an environmentally-conscious hybrid.

Called the B5-TPH, for ?Turbo Parallel Hybrid?, the three-door coupe combines a 260 PS 2.0 litre ?boxer? engine with an electric generator/motor fitted between the engine and transmission.

This provides a low-cost solution to giving driving enthusiasts lively acceleration and a high top speed but with excellent fuel consumption and low exhaust emissions.

The four-cylinder horizontally-opposed petrol engine features a Miller Cycle system which improves engine efficiency by reducing pumping losses thanks to a combustion expansion stroke that is longer than the compression stroke.

Normally this system makes an engine sluggish at low speeds but thanks to the electric motor, standing-start torque is boosted beyond even an Impreza Turbo?s.

The electric motor itself produces 10 kW and 150 Nm torque while the petrol engine has a 191 kW output with 343 Nm torque.

A new type of manganese lithium ion battery charges to 95 per cent capacity in five minutes and operates not just in city driving but also when cruising.

The design of the Subaru B5-TPH itself is a striking one featuring smooth contours and a large tailgate, hinged just behind the B-post.

Its ?crossover? theme combines the practicality of a hatchback, fun of a coupe and all-terrain ability of a SUV, complete with a 200 mm ground clearance.

Meanwhile, Subaru?s much-admired full-time symmetrical all-wheel drive and low-centre-of-gravity ?boxer? engine ensures agile handling.

But while the B5-TPH continues the theme of previous concept cars such as the B11S and B9 Scrambler, the concept is not meant to hint at any future Subaru models.

More images here:
Suburus are looking a lot like Sabbs these days...or is it the other way round :?

This one looks like the Sabb 9X Concept to me