[Yo-Yo]

It looks like an overgrown automotive AC compressor. No mention of emissions or fuel efficiency.

AC Compressor operation

[Red Badger]

From Their website:

What about emissions?

Like the Wankel rotary our combustion chamber is unencumbered with valves and such like. However unlike the rotary we approach a near optimal chamber shape far closer to a conventional 4-stroke engine. Therefore we achieve a much more complete burn than a rotary.

Charge motion development will further improve our combustion efficiency to approach that of a conventional 4-stroke.

There is currently some oil required for the seals to work and this can add to the emissions, however our consumption is far less than that required for a 2-stroke or rotary.

[jjotto]

Of interest:

http://articles.sae.org/13429/

[Demiurge2]

My thought as well - sounds like a wobble compressor.