Not to hijack the thread but there is also something very interesting in this interview:
MT: What about below the M3 and M4?
FN: There’s no decision yet. But I absolutely want to develop a successor model to the 1 Series M Coupe. I have all the components I need – the powertrain, chassis. In the near future you will know. We can’t call it the M1, because that number is for the special mid-engined car, but there is M2, isn’t there?
MT: What about a four-cylinder M car?
FN: Not in the near future. But it’s possible. Our engines are modular.
So he kind of confirms the M2, and he seems to confirm that it won't be a 4 cylinders.
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