This engine is 20% more efficient than anything of it's type that NASA is using. I am posting it here because the accompanying image is fucking rad.

Excerpt From NewScientistSpace
XCOR Aerospace has test fired an early version of a rocket engine fuelled by liquid methane and liquid oxygen (LOX). Such engines may one day be used to efficiently launch spacecraft to and from the Moon and Mars.

The LOX-liquid methane combination is about 20% more efficient than traditional "hypergolic" fuels, which ignite on contact. "If you run the studies on paper, it's quite clear methane/liquid oxygen has the potential to have greater performance than a hypergol engine," says Richard Pournelle, director of business development for XCOR.