The 2010 Mercedes-Benz S400 Blue Hybrid

It's probably best to call the new Mercedes-Benz S400 BlueHybrid a mild, rather than full, hybrid, because it can't propel itself on electrical power alone. In other words, the BlueHybrid is not powered by the two-mode system co-developed with GM for big SUVs, which will be an option for the M-Class next year. This is a smaller, cheaper system designed to be scaleable across all Mercedes car lines. Despite its comparative simplicity, the S400 BlueHybrid's gasoline and CO2 savings are significant: some 21% in the European test cycle, compared with the regular V-6 S350. It's also quieter at rest and more muscular in real-world acceleration. There's very little penalty over the standard V-6 in terms of weight -- just 170 lb -- and none at all in passenger or luggage accommodation or payload.