Originally Posted by
kevinsac
Wrong, and ....wrong, too.
Z fares are upgradeable.
But sadly only with miles + copay or UDU (most domestic flights). SWUs/CR-1s can't be used. On 777 flights that is still a good deal, not so much on 747/767 flights. Op-ups do happen quite a bit, though, since Z puts you into paid business.