2010 PORSCHE CAYENNE HYBRID: Even sports cars are keen to go green

BY Clare Dear. Apr 17 01:00 am

STUTTGART -- It's no surprise mainstream carmakers are embracing the shift to green, but who would have thought a premium sports car brand such as Porsche would be keen to go green? Yet, here I am, driving a pre-production hybrid version of the German automaker's Cayenne SUV, a product Porsche expects to have in dealer showrooms by late 2010.

In a market that's high on such purposeful hybrid people-movers as the Toyota Prius and Honda Insight, combining high-performance products and hybrid technology isn't the expected norm, but Porsche says its advances into this field won't compromise its traditional values, including delivering the exciting type of performance its customers expect.

With the Cayenne project, Porsche has combined its best engineering expertise with colleagues at Volkswagen Group (including Audi) to explore new hybrid technologies. The result is a parallel system unlike any other hybrid in the world. Michael Leiters, the general project manager for the Cayenne Hybrid, says what distinguishes the Porsche system is a disengagement clutch that allows the powertrain to freewheel or coast at highway speeds, further improving fuel efficiency, compared with other hybrid systems that remain "connected," thereby creating engine drag.

Where the engine management system in a conventionally powered vehicle system has about 5,000 data labels, Leiters explains that Porsche's hybrid management system is five times more complex. He offers this example of the effectiveness of the clutch disengagement system: "Imagine driving along at 140 kilometres an hour with a cup of coffee in the cup holder. You depress the clutch pedal, shut the engine off and coast. Then turn the ignition back on and let out the clutch -- the resulting lurching action as the engine refires and the clutch is released will send the coffee spilling in all directions. With our system, the engine is restarted in 300 milliseconds and the re-engagement is absolutely smooth. You won't spill a drop."

On the road, the system lives up to Leiters' billing. Cruising on a highway here at 110 km/h and lifting off the go-pedal just a hair results in complete engine shutdown -- Porsche engineers call it "sailing." It's a bit strange to see the speedometer reading 100-plus and the tachometer registering zero, but, with the clutch disengaging both motors, the Cayenne quietly sails along, saving fuel.

The Cayenne's powertrain consists of a 3.0-litre supercharged V6 -- the first supercharged combustion engine in a hybrid, says Porsche -- and a 38-kilowatt electric motor, which also functions as the starter and alternator. The V6, sourced from Audi, kicks out 333 horsepower on its own, but, combining it with the single triple-phase electric motor, which contributes 210 pound-feet of torque at startup, generates a total output of about 374 h.p., delivering the acceleration and highway response one expects from this premium sporty brand.

 

-- Canwest News Service