Isn't this just a Diesel-style engine??? If yes, then of course it would see a boost in MPG.
EDIT - never mind. I see it's using gasoline. Hmmm. A gasoline engine that acts like a diesel (compression ignition). Cool concept! Unfortunately it looks like we won't see one on the market until around 2020.
The main challenge left is above 4000 rpm.
Diesel has the same problem. Diesel engines rarely go above 4000 rpm, because the gases do not expand that quickly.