Where did you get that the Mondeo uses the same platform as the Mazda6?
Honestly, I don't know too much about the Mondeo, but from what I do know, the Mondeo has nothing related to the Mazda6 in anyway platform-wise. I even have a few of the latest-gen Mondeo's suspension schematics (unfortunately I can't show them to the public), and it's far different to the Mazda6 one. On the engine front, there are a few common engines, 2 diesels and some gasoline engines may share the same block but that's it.
There are discussions about merging the Mondeo and Mazda6 onto the same platform, and it does make sense, but that's more in terms of the future (not the current-gen).