The Incredible Shrinking Engine.

Honda?s HCCI (Homogeneous Charge Compression Ignition ) test engine - relies on a lean air-fuel mixture that is compressed until it self-ignites like a diesel engine. For Daniel Cohn, a senior research scientist at MIT's Plasma Science and Fusion Center, the century-old internal-combustion engine is still a source of inspiration. As he strides past the machinery and test equipment in the MIT Sloan Automotive Laboratory, his usually reserved demeanor drops away. "An engine this size," he says, pointing out an ordinary-looking 2.4-liter midsize gasoline engine, "would be a rocket with our technology."