Steam Hybrid Car from BMW

Now here's an interesting tidbit read over at Slashdot. BMW is unveiling its turbosteamer hybrid engine, which uses the excess heat in the exhaust system and reclaims 80% of it by powering a steam engine that assists the gas engine. Overall, this gives a 15% more efficient engine; and significant additional performance (power and torque) with practically no downside. "This project resolves the apparent contradiction between consumption and emission reductions on one hand, and performance and agility on the other," commented Professor Burkhard Goschel. So, what do you think, could steam engines be the future of environmental-friendly hybrid vehicles?