The Mercedes S 400 hybrid vehicle is scheduled to be released in the U.S. this summer.

The choices for high-performance environmentally-friendly vehicles are beginning to grow.

Mercedes-Benz is launching its first passenger car model equipped with a hybrid drive system in the summer of 2009 – the S 400 BlueHYBRID, the company announced.

Powered by a combination of a modified V6 gasoline engine and a compact hybrid module, the S 400 BlueHYBRID, the company boasts, will be the world’s most economical luxury sedan with a spark-ignition engine.

Another nifty looking environmentally-friendly performance car is set to be unveiled next month, albeit an electric vehicle – not a hybrid.

Tesla Motors, the maker of high-performance electric vehicles, announced that they will be unveiling their Model-S sedan on March 26 at Space Exploration Technologies in Hawthorne, California.

Based on the S 350, the new Mercedes-Benz S 400 BlueHYBRID features an extensively modified drivetrain.

The sleek-looking vehicle will offer high performance in luxurious comfort, while at the same time lessening the burden it has on the environment.

The hybrid vehicle will also have the lowest CO2 emissions in its performance class – just 190 grams per kilometer.

The hybrid module also has a comfortable start/stop function, which switches the engine off when the vehicle is at a standstill – for example at traffic lights. When it’s time to move off again, the electric motor almost imperceptibly restarts the main power unit.

This likewise makes a contribution to fuel economy and environmental protection: because the engine restarts first time, and practically instantly, emissions are also minimized during the starting phase, Mercedes announced in a press release.

The driver is also able to monitor the status of the hybrid drive system visually. The instrument cluster has a separate, centrally positioned, display showing the energy flow during boost and recuperation phases, as well as the battery charge status.

The 12-Volt lead/acid battery is installed in the boot, and thanks to its interaction with the lithium-ion battery, it is considerably smaller in size and lighter than usual.