Porsche has been trotting out its prototype Cayenne Hybrid in Europe for much of this year, but yesterday in Los Angeles we got our first look at it on U.S. soil. Porsche management board member Dr. Wolfgang Duerheimer told us about the Cayenne Hybrid, which will go into production toward the end of this decade. In many respects, the parallel hybrid system is fairly conventional with a nickel metal hydride battery pack, although the packaging is fairly unique as the motor's mounted with the rear differential. From a performance perspective, Porsche is aiming for a 30% efficiency improvement on the EU combined cycle with a rating of at least 26 mpg (US). What really sets Porsche's hybrid system apart, though, is the ability to shut off the engine when cruising at speeds up to 75 MPH. The Cayenne can potentially cruise the autobahn on battery power alone for several miles if conditions allow for it. Other hybrid systems only allow EV mode up to about 30 mph. It will be interesting to see how well this works in the real world, and whether or not a light right foot will allow you to accelerate up to 75 MPH on battery power alone.