BMW has developed a new type of "hybrid" technology, using centuries-old ideas. According to a recent SpeedTV.com article, BMW Group Research and Engineering has taken advantage of the heat generated by a normal internal-combustion engine and used it to generate steam. Essentially, they've replaced the electric motor in a "conventional" hybrid with a steam engine. This is significant because it puts no extra load whatsoever on the existing engine. Additionally, the components involved don't take up a significant amount of space. Here's a diagram that, while in German, gives a pretty good idea of the size of the additional equipment.
According to the article, the system in its current form will fit a current-generation BMW 3 Series equipped with the four-cylinder engine. Following additional development, BMW hopes to further improve the packaging of the system to make retrofits to existing cars possible.
This system breathes some new life into the internal-combustion engine, and reminds us that regardless of the leaps and bounds being made in alternative power technologies, we're a long way from fully tapping the potential of our existing engines.