The Mercedes S400 hybrid with a Lithium Ion battery will hit dealer lots in September 2009 according to the August 2009 Issue of Motor Trend, page 116. The power and EPA mpg is nothing special and nothing to brag about; however I consider this "a start." At least Mercedes is beginning to sell a hybrid version of one of it's mainstream cars. I hope to see more progress in the future. For those that are interested, the S400 hybrid will begin at $90,000. EPA 23/33 mpg. 3.5L V6 producing 275hp/255lb-ft, electric motor producing 20hp/118lb-ft, for a total output of 295hp/283lb-ft. The vehicle weighs 4600lbs. Automobile Magazine, August 2009, has a comparison of the S400 Hybrid with the Lexus LS600hL. The title of the article is "Battery-Assisted Barges." Yes, the image is not very good. Go look at the actual magazine or find it online.
From an engineering standpoint, the ratio of gas to electric power is more like the GM hybrid-lites. This Mercedes ratio is too weak to offer any significant fuel savings. The EV is in the range of a starter motor without the ability to improve low-end torque or regenerative braking. In contrast, the smaller Honda hybrids have a better gas-to-electric power ratio. Honda correctly uses the significant motor power to fill in the low-end torque of a light-weight, small displacement engine. It isn't in the Prius range but much better than the 10-to-1 ratios found in 'green wash' hybrids. Bob Wilson