Re: Turbo engine for other models?
Kinda doubt it
The logic is this...
M3 is the BMW M-division bread and butter ( not the M5 nor M6 which are at much price brackets )
So, to main exclusivity of the M5 n M6, people are "forced" to dig into a deeper pocket to afford the cars as opposed to the M3 which is much more affordable at mass market level. A similar argument can be said about the Z4M tho I'd like to see the same engine in one of the variants too but again, I think it's very unlikely.
And given the 3 series are BMW's best selling models,...it makes more sense to close the gap amongst the variants ranging from 320 323 330 335 to M3 in order to penetrate a much wider market segments.
I could be wrong but I am just speaking from a more feasible marketing point of view.
Cheers