Came accross this engine idea - they "claim" to have a major asian maker onboard.
Also claims to be 25 - 50 % more fuel efficient.
looking at it it operates as a "twin" 3 cyl - although operating with 2 crankshafts, the intake spark and exhaust are shared / dual port heads.
I would imagine would not run as smooth as we are used to though
http://pinnacle-engines.com/technology.html#