I wouldn't put either free valves or the "wave disk" engine on the list of technologies likely to affect mass produced ICE efficiency in the next decade or two.

I wouldn't put either free valves or the "wave disk" engine on the list of technologies likely to affect mass produced ICE efficiency in the next decade or two. HCCI/SCCI gas engines with VVT, variable displacement, and cylinder deactivation are very close to full scale production though, and promise very substantial improvements. Mild hybrid (electric regenerative braking and assist with a small battery/large capacitor) gives another boost, though at a substantial complexity cost (not nearly as bad as a full hybrid though).