Having personally spoken to the engineers on this project (F10 M5), they are currently (and have been) exploring the V10 and V8 routes for this vehicle. Here is an inside tip- if the German "clause" in the US emissions rules goes into effect it may be a V10- if not we will see a TT V8, to deal with the emissions issues. They can get performance of the V8 up there but from a marketing standpoint the V10 is a kick in the pants of other brands. The V10 will be smaller in displacement than the current engine and be turbo charged as well, featuring a trick induction system similar to the CCM on the X5/X6 ///M.
Having experienced the X6 ///M extensively it think many narrow minded "enthusiasts" will be impressed by that motor, it is ridiculous.
On a side note- Whoever thinks that the current ///M3 is unispired/lackluster is clueless and has either never driven it or does not get it, it is by far the best ///M yet though the steering is a bit over boosted at times....
I still prefer the current M3 to any other product out there, it will compete with cars twice its price- enough said.
-M
