Mercedes S400 BlueHybrid Coming Next Summer

Mercedes-Benz announced that its S400 BlueHybrid will hit European dealerships in the summer of 2009 and will arrive on U.S. shores shortly thereafter. The mild hybrid will couple a seven-speed automatic transmission with a 20-hp electric motor, for an expected combined mileage of 29.8 mpg. The current U.S. S500 gets 16 mpg combined, but Europe has a less-powerful gasoline version.

This would make the S400 the fuel-economy leader in large luxury sedans, as well as the first vehicle to hit the market using a lithium-ion battery. If you’ve been keeping up with news of the Chevy Volt, you’ll recall that lithium-ion batteries are all the rage. For all that rage, though, Mercedes-Benz will become the first automaker to put a production vehicle on the road with the new type of battery — a full year ahead of GM’s Volt. Other companies, including Audi, are also working on lithium-ion products, but none have a definitive release date.

The battery will not only assist the engine but, along with regenerative braking, will provide power for other electrical accessories. No word on pricing yet, but our guess is it will not be cheap.