Cool engine design, but the thread title is oddly worded - this engine would be used in a hybrid car, by definition. It would make sense to have it in a plugin hybrid - and it would be a serial hybrid, by definition.
It bypasses the whole crankshaft / offset vector problem, and it has no camshaft, or valve springs, either. Much lower parasitic losses. I wonder if it uses a magnetic or an air spring to return the piston to TDC? Edit: it is a gas spring - I shoulda' read the whole article.
It does appear to be a 2-stroke but it also has electrically (pneumatically?) actuated valves, so it is unlikely to "leak" unburned fumes out through the exhaust.
More info here:
http://www.greencarcongress.com/2014...0422-fpeg.html