So Achates Power, in San Diego, is working on a diesel engine that uses 1/3 less fuel than conventional engines:
The basic Junkers design has an unusual arrangement of pistons. In a conventional engine, a piston moves inside a cylinder, compressing fuel and air against a cylinder head. A significant amount of energy in fuel ends up heating the cylinder head rather than driving a piston. The Junkers design puts two pistons in the same cylinder and eliminates the cylinder head. Instead, the two pistons compress fuel and air between them and then fly in opposite directions when the fuel is combusted.
I love that the name of the German company that’s the source of Achates design is named “Junkers.”
(This article is from January, but I’m posting it anyway. I’m way behind in links)