Porsche Tells More About 2010 Cayenne S Hybrid: 86 MPH With the Engine Off!
By John O'Dell February 20, 2009
Porsche has released a few new details about its upcoming Cayenne S Hybrid, not the least of which is that, in testing, the full hybrid system enables the big SUV to run in all-electric mode at 86 miles an hour and to achieve average fuel economy of 26 miles a gallon in the European testing cycle.
U.S. fuel economy figures haven't been released but are likely to be a bit lower -- early testing put the combined average at about 24 mpg,
The SUV, shown initially in the U.S. at the Los Angeles auto show late last year and slated to hit the U.S. market in 2010, will use a supercharged Audi 3.0-liter V6 direct-injected gasoline engine that cranks out 333 horsepower and 324 pound-feet of torque.
It will be augmented by a 52-hp electric motor that provides an additional 221 lb-ft of torque.
An eight-speed automatic transmission ties the power plants together and the electric motor also serves as an alternator to help top up the charge in the hybrid SUV's 154-pound nickel-metal hydride battery pack.
Porsche's hybrid system sandwiches the electric motor between the internal combustion engine and the transmission, much as Honda does with its Integrated Motor Assist hybrid system.
The difference is that while Honda's system initially kept the gas engine running all of the time (that's been modified recently and Honda's hybrids can now run in all-electric mode for brief periods at low speeds), Porsche uses a clutch that allows the engine to stop at highway speeds while the electric motor soldiers on when there's sufficient juice in the batteries to power it up.
It is called a parallel hybrid system because the electric power plant and internal combustion engine can operate simultaneously, or in parallel.
Porsche's complex electronic controls and hybrid system design enables the system to provide a lot of its electric assist -- and fuel economy boost -- at highway speeds while other parallel systems; such as that used in the Prius and other Toyota hybrids, concentrate on adding electric propulsion during low-speed city driving.
Porsche said the Cayenne S Hybrid can travel about 1.2 miles in all-electric mode. At full acceleration, with both the supercharged engine and electric motor providing power, the SUV can hit 62 miles an hour from a standing start in 6.8 seconds.
A similar hybrid system will be used in the hybrid version of Porsche's four-door Panamera touring sedan. The conventional Panamera is scheduled to hit the market later this year and the hybrid will follow "sometime" after, the automaker said.
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