Attendees at next week’s 2009 Frankfurt auto show will witness a showdown between Germany’s luxury automakers, but while this is to be expected considering it’s a German event, the row between the automakers will center around their respective visions for future, ecological motoring rather than the traditional horsepower wars.

Mercedes-Benz is expected to have one of the biggest displays, with plans to unveil the previous trio of BlueZERO concept cars as well as the hydrogen-powered B-Class F-CELL. Today Mercedes revealed the plug-in hybrid version of its S-Class sedan, supplementing information leaked late last night.

Featuring similar technology to its S400 Hybrid production car sibling, the new concept, which has been labeled the 2009 Mercedes-Benz Vision S500 Plug-In Hybrid Concept, returns a claimed fuel economy of 73.5 mpg. Even with that frugal rating, the S500 plug-in is a performer, capable of 5.5-second runs to 62 mph and a top speed of 155 mph.

According to Mercedes-Benz chief Dr. Dieter Zetsche, "The Vision S500 Plug-In Hybrid is a new milestone on our path toward zero-emission mobility. It is a luxurious and safe S-Class vehicle that offers superior driving performance while at the same time consuming less fuel than current compacts. All of this shows that our top models will also be able to combine automotive fascination with responsibility for the environment."

The company describes the technology as "near production," meaning it's not quite ready for prime time.

The advanced powertrain combines a 3.5-liter V-6 gasoline engine with an electric motor running on lithium-ion batteries. This unique setup will allow the Vision S500 Plug-In Hybrid to travel up to 18.6 miles on electricity alone. A rapid-charge setup allows the car to take a full load of electrons in just 60 minutes, but requires a 20 kilowatt source. A standard household outlet, which supplies closer to 3.3 kilowatts, takes about 4.5 hours to charge the battery.

When the battery is depleted, the 60-horsepower hybrid module will activate the V-6 engine and allow it to act like a conventional hybrid. A second clutch between the electric motor and combustion engine allows them to operate together or separately.


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