all Wellington area electric multiple units are now owned by the Wellington Regional Council

That was the effect of part of an agreement signed last week with KiwiRail and the Government: the Greater Wellington Council is taking over ownership of the Ganz Mavag and English Electric trains from KiwiRail and committing to upgrade the Ganz Mavag units at a cost of $80 million.  What this upgrade will comprise wasn't specified in the media release.  (One significant deficiency of the present trains is the lack of a public address system inside the cars.) The new Matangi units are already owned by the Regional Council.