Is "virtual displacement" the same as the swept volume (*) and virtually nothing to do with the actual volume of the cylinders.
(*) piston travel times cross section area of cylinder
I dont believe so. From what I can tell, it is currently related only to kW output - hence why a PHEV with an electric motor, can also have a virtual displacement.
Although in the past, BMW have seemed to change the nomenclature on a whim to suit the market segment:
https://en.m.wikipedia.org/wiki/List_of_BMW_vehicles (see under nomenclature)