And they're not hybrids: HCCI engines could bring breakthrough fuel efficiency

摘要

Researchers at all the major car companies and U.S. labs are trying to perfect homogenous-charge compression-ignition technology (HCCI) in the quest for more fuel-efficient internal combustion engines. Like most auto engines, HCCI engines inject a pre-mixed charge of fuel and air into the cylinder. But combustion is not set off by a spark plug. Instead, the mixture is compressed until it au-toignites, much like in a diesel at a much lower temperature. This virtually eliminates NO_x emissions and lowers throttling losses, which could lead to a 30% boost in fuel economy. HCCI engines would also use a higher ratio of air to fuel, high compression ratios (on the order of 12:1), and burn a variety of fuels, including methane.