I was looking for seat map on CX873 in July 7, w/ the aircraft as 77W. Is that seat map correspond to a Premium Economy?
It looks similar to this seat map with premium economy:
CX 873 on July 7 does not have a PE cabin, regardless of what the equipment code is, as there are no W,E,R classes being sold on that flight. Also the economy cabin on that flight ends in row 67, not 72, so that is not the same aircraft.
If a PE cabin exists on a CX flight, ExpertFlyer can now show it.