Scribbled Atom

In a car engine, only 15% of fuel gets used for propulsion. A team at Michigan State University project they can get to 60% by replacing pistons with a rotary disc. The prototype "shock wave combustion generator" cycles through shock waves and explosions to turn fuel into electricity, potentially for hybrid vehicles.
(More info from New Scientist, from the US Department of Energy's Advanced Research Projects Agency grants page, and this erratic 2009 MSU video).