Porsche Cayenne Hybrid

Within two years, you'll be able to go 'sailing' in a Porsche Cayenne Hybrid without any intervention from its internal combustion engine at speeds up to 120km/h.

That's the promise offered at the preview of the first 'green' Porsche just held at the company's research and development centre at Weissach, near Stuttgart.

You'll also use nearly 25 per cent less fuel, accelerate to 100km/h 0.5 seconds quicker than a Cayenne equipped solely with a similar petrol engine and have a stump-pulling 550Nm of torque at your command from the same V6 operating in full hybrid mode.

Porsche's take on hybrid power comes in the wake of criticism from some quarters that the company has been sitting on its hands, while companies like Lexus prick consciences and get golf club bragging rights in the company's critical US market with their green alternative.

By-passing the diesel option, which they say would be an anathema to a sports car maker "because the fun stops at 4,500rpm", Porsche has become an equal player with Volkswagen (of which it owns nearly 31 per cent) and Audi (which is fully owned by VW) in developing parallel full hybrid technology based on the VW built 3.6 litre V6 FSI engine for use in vehicles from all three product ranges.

Which of the three will actually get to market first is still a guarded secret, but Porsche has already promised a hybrid Cayenne by the end of the first decade of this century and as the maker of socially challenging sports cars and conspicuously large SUVs, its PR and market needs are more pressing than those of its partners. Yet you can still confidently expect to be able to purchase a hybrid Touareg or Q7 around the same time, which could be as early as two years from now.

Parallel hybrid differs from the power-split system currently employed by Toyota and Lexus in that the electric motor sits immediately behind the engine and ahead of the transmission. This option is understood to have been investigated by Toyota, but discarded because of difficulties in obtaining an acceptable jerk-free transition from electric to internal combustion engine drive.

In the Weissach test track, the Cayenne Hybrid can start in electric mode and drive silently and entirely dependent on its stored energy at speeds to 70km/h, beyond which the petrol engine cuts in more seamlessly than an upward shift of the car's standard six-speed Tiptronic transmission. At constant speeds up to 120km/h on a flat or downhill gradient, the internal combustion engine will cut out entirely, with the cayenne eerily 'sailing' without any form of propulsion until the forces of wind resistance, gradient or driver intervention bring it back into play.

Flooring the accelerator from a standing start produces instant and vigorous acceleration, with the sophisticated Hybrid Manager (which delivers 20,000 data parameters compared to a convention engine's 6,000), instantly transferring sole drive responsibility from the electric to the internal combustion engine.

The combination of the 206kW V6 and 34kW electric motor enhances acceleration compared to a conventional car, chopping 0.5 seconds off a regular Cayenne's 0-100km/h dash and delivering 550Nm of torque at 1,500rpm -- 50Nm more than that developed by a regular V8 Cayenne S.

Despite this, fuel consumption in production versions in the combined European cycle will be as low as 8.9 litres/100km. Compared with the current Cayenne V6's 12.9l/100km.

The other major advantage of the parallel hybrid path for Porsche, VW and Audi is that their system fits easily into the existing Cayenne/Touareg/Q7 platform. As the battery sits in the existing spare wheel well, there's no loss of luggage space, no reduction in fuel tank size and no external clues to the hybrid power except the badging.

For Porsche it's the dream solution -- the green vote with enhanced sportiness.

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