[GuidoK]

At least I can backup something...
There's nothing vague about that post. You cant proove its not from that car. You cant proove that he didnt know what car he was working on, basically you're saying he apparantly was too blind to see the difference between an e46 and e85. I think those people usually dont break up diff cores.

You cant backup anything, and have no in depth additions...
The only thing you can do is react to technical data I bring into play, by denying it on grounds of so called plausibility.... because you cant come up with hard techical data yourself.
You probably dont even know what an 188 or 210 diff means or even what other diffs are in that range.
You have no idea what you're talking about. You know nothing about bmw drivetrain mechanics.

The only thing I can say is that if they wanted to have an e89m, it would mean that it would require to make a bespoke rear subframe, with a bespoke rear diff, because none of the cores they have on stock would have fitted. And they've never done that with any /m in the Z range. If they had gone with a 1/3 series back axle in the e89 instead of the x3 style, they could have just put the m3 back axle in, like they did with the 1m and previously with the z4m.
Thats how they build those cars. And being that there didnt came an e89m they didnt stray from that strategy.
As for marketing potential for an e89m they could have used the race succeses of the e89 GT3 to boost sales, but apparantly it was too big of a hurlde to take as the e89m never came.