Apparently this thing is capable of putting out around two horsepower per pound of motor. They say at it's current size of 18" in diameter and 24" in length it puts out 300 horsepower and gets 70 MPG.
The nice thing is it's air cooled (doesn't get that hot) and has very few moving parts.
Imagine something half the size capable of 150 horsepower in a space less than a cubic foot with no liquid cooling system to worry about.
Duesenberg is using the design for both a car and a motorcycle currently in the works.