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Tuesday, March 10, 2009

2011 Porsche Cayenne S Hybrid First Drive

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One or the Other
For the most part, Porsche's approach to the hybrid is a straightforward parallel system, though it's more like that in the new Honda Insight than the more sophisticated technology of the Ford Fusion Hybrid and Toyota Prius. The Porsche system differs from Honda's IMA arrangement in that a clutch between the engine and the electric motor allows the V6's crankshaft to be stopped. (The Honda system instead reduces pumping losses by using a VTEC motor to shut the valves while the crankshaft continues to turn.) In any case, stuck between the Porsche's supercharged, 333-horsepower, direct-injection 3.0-liter V6 engine and the eight-speed automatic transmission is a three-phase synchronous electric motor rated at 38 kilowatts (52 hp).

When both the electric and internal combustion engines are working together, there's up to 374 hp available for acceleration. Under deceleration or braking, the electric motor acts as an alternator and feeds juice to charge the 240-cell nickel-metal hydride battery array that's nestled behind the rear axle where the spare tire would be stowed in a conventional Cayenne.

The all-wheel-drive Cayenne S Hybrid has 84 hp more than the base-model Cayenne with its 3.6-liter V6. It has just 11 hp less than the Cayenne S with its 385-hp 4.8-liter V8. Of course this output is still some way from the 405-hp Cayenne GTS, 500-hp Cayenne Turbo and the somewhat insane 550-hp Cayenne Turbo S.

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