Second Drive
Two years ago, Porsche unveiled a concept of its first hybrid, a Cayenne V-6. It came with a single electric motor slotted between the engine and the automatic transmission. That went against the prevailing “power-split” hybrid wisdom practiced by Toyota and Ford, whereby a gasoline engine interacts with a pair of electric motors to form a continuously variable transmission. Porsche says two advantages of its system are that it enables the Cayenne to retain its towing capacity and conventional all-wheel-drive system.
We spent a day driving the production Cayenne that’s powered by the 333-hp, 3.0-liter supercharged V-6 in Audi’s S4 rather than the Volkswagen 3.6-liter V-6 in the concept. Mated to a 52-hp electric motor, it gives a maximum output of 374 horsepower, enough grunt for a claimed 0-to-60-mph time that’s just 0.4 second slower than the V-8–powered Cayenne S’s 6.0 seconds. An eight-speed automatic transmission takes the place of the six-speed unit in the concept. This powertrain will later find its way into the upcoming Panamera.
Like many hybrids, the Cayenne can be driven solely on electric power up to a speed of 30 mph for the most feather-footed drivers. To enable efficient regenerative braking to charge the 288-volt nickel-metal hydride battery, the torque converter locks up very early, but Porsche had to painstakingly tune the shifts to avoid jerkiness in this mode.
One of the key features of the Cayenne hybrid is its ability to coast at speed to eke out better gas mileage on the highway. At speeds up to 86 mph, the engine will shut down, only to be restarted when the driver asks for torque by stepping on the gas pedal. In order to do this smoothly, a clutch between the engine and the electric motor reengages as the engine fires, a process that Porsche says takes 0.3 second.
The company claims the vehicle averages 26 mpg in the latest European combined cycle—a 27-percent improvement over the nonhybrid Cayenne V-6—which is very impressive for a 5700-pound SUV. (That’s about 350 pounds heavier than the V-8 Cayenne S.)
We found that the hybrid system works very well. There’s just a slight whine to indicate that the Cayenne is operating in electric mode, and it moves seamlessly between gasoline and electric power. Under hard throttle, the vehicle gets along smartly, the torque from the electric motor impressively augmenting the smooth and sonorous V-6.
The electrohydraulic power steering is a touch light, but this is still a very sporty SUV. On the highway, it’s eerie when the engine goes quiet while coasting, but reengagement of the gasoline engine is amazingly smooth. Our only reservation was the occasional clunky downshift while braking from low speed, no doubt caused by the locked torque converter as energy is redirected into the battery. Porsche claims this is a prototype glitch.
The hybrid Cayenne S will cost significantly more than the standard $60,215 ÂCayenne S. We estimate a base price of about $70,000.
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The battery is housed where the spare used to live.
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