Mercedes S400BlueHybrid - Watch out, Lexus... - 2008

If you're uber-wealthy and laden with at least a little bit of eco-conscience (or just want to beat the congestion charge), there's only ever been one luxo-barge choice: the Lexus 600h.

But now there's a new player in the massive hybrid game. This is the S400 BlueHybrid, Mercedes' first-ever passenger hybrid and, by Merc's reckoning at least, the most economical luxury petrol saloon in the world.

Based on the S350 but with additional electric bits, the S400 gets a 3.5-litre V6 mated to a electric motor with a snazzy set of lithium ion batteries - the first production car to get such batteries.

It's certainly at the 'mild' end of the hybrid scale - the electric motor provides 19bhp along with a more useful 118lb ft of torque from 0rpm. It can work with the V6 to provide a total output of 295bhp and 284lb ft of torque - good for a 0-60mph time of 7.2 seconds and fuel consumption of 36mpg. If that doesn't sound too impressive, remember that the Lexus 600h barely tops 30mpg.

There's plenty of other clever green tech in the S350, too, including a BMW-style stop-start function and regenerative braking to eke out every last drop of fuel.

All of which sounds rather sensible, but Merc is making a big thing of the S400's sporty nature, and reckons that all the low-end torque should make it a laugh on the back roads.

We'll find out if they're right when the S400 reaches the road next summer. The LS600h will be lying in wait...