Mercedes-Benz S400 BlueHybrid: Smells like Lithium Ion

Mercedes is gearing up to release the BlueHybrid S400 -- its first hybrid car. What's more, it looks as if this sucker will be the first production vehicle to use lithium-ion batteries instead of the nickel metal-hydride cells found in things like the Toyota Prius.

This is pretty big news. The NiMH battery assemblies most hybrids and all-electric vehicles use, like the G-Wiz, are heavy and occupy a huge amount of room -- the entire floor in many cases. The BlueHybrid S400's Li-ion pack is roughly the size of an ordinary car battery, so it's lighter and fits snugly under the bonnet.

The battery pack powers a 15KwH (20bhp) electric motor, which when combined with the BlueHybrid S400's 3.5l V6 engine, produces a very respectable 299bhp. That allows for a 0-60mph time of 7.3 seconds and emissions of just 190g/km of CO2. To put this in context, today's equivalent S350 produces a comparatively lame 262bhp, and a lung-destroying 242g/km of CO2.

Our only concern is the fact the S400 doesn't dramatically improve fuel economy. Currently, it promises around 30mpg (combined) which isn't that far removed from the S350's 28mpg. Still, it goes about its business in a much greener fashion, and hopefully Mercedes-Benz can eek out better fuel economy before it's released.

If the BlueHybrid S400 can deliver on its Lithium-Ion promises, we'll be impressed -- not least because it bodes well for more affordable hybrids in the future. The BlueHybrid S400 is due for release midway through 2009. Start saving your pennies (at least 6,178,500 of them) now. -Rory Reid