Mercedes Benz will be launching its first hybrid, the S400 BlueHybrid next spring and Phil Floraday from Automobile got a chance to sample it on a recent trip to Europe. The S400 is a mild hybrid, and in many respects it's more similar to the Honda IMA system than Toyota's Hybrid Synergy drive. The S400 will be the first mass-produced hybrid with a lithium ion battery pack. As Phil explains, the system provides start/stop capability, and some electric boost. However, the main purpose is to drive vehicle electrical systems off the lithium battery, reducing the parasitic loads on the engine. The battery itself gets most of its charging from regenerative braking that provides 75 percent of the braking capability in most urban driving.