For technical aspect on any new 1M, I'd rather see a turbo-4 (petrol) than the high-revving straight-6. Especially if that I-6 is the steel-blocked version from the previous M3.
I badly want to see a new Inline 6, high revving M block. And it won't be the steel one used in the previous M3, but the new magnesium/alu block used in the current 272 hp 3.0 I6 which will be pretty damn lightweight compared to the old E46 block.
If the new M V8 weighs less than the old I6, it's pretty clear BMW will do some weightsaving wonders on a future ///M Inline 6 too.
374PS / 1260kg sounds too good to be true....I'm praying already
Please BMW, the Inline 6 is argueably the most praised engine ever conceived. It has to return in modern form.