No spark, no ignition, and 30% better fuel economy...
Hybrid fuel economy without all that complex stuff, or use it in a hybrid for uber mileage...
http://www.popularmechanics.com/automotive/new_cars/4261288.html?series=19It requires the engine to have variable valve timing and direct injection.
Two things that exist on the new Cadillac CTS (look how well that worked out...).
The extra item needed is the control of pressure in the cylinder. Could be with us within 10 years.