I have to say I don't understand it - current Zafira is built off the Astra-J (Delta II) platform with the Astra-K about to launch - current Meriva is built off the old Gamma platform which goes forward under the Mokka/Trax/Encore despite the new Corsa-E retaining the Fiat SCCS platform from the outgoing Corsa-D.
One of Opel's main issues is space production capacity so I don't see any advantage sharing with PSA when Opel already has suitable platforms and engines which will stay in production for other GM models.
Specifically, it means that Opel/Vauxhall will be selling sub-compacts built on three different platforms - Mokka on Gamma, Corsa on SCCS and Meriva on PSA.
