Originally Posted by Red Bread
Did you sleep through the whole S85 V10 era? Not saying that we're seeing a V6 here, but using a non-series motor is sort of the whole point of M prior to the X5M/X6M, 1M and F10 M5, the S85 probably being the most bespoke of the lot.
Actually, almost all the M engines have been based on series production motors. The E46 M3's S54 was derived from the M54, E36 M3's S50 from M50, and the E30 S14 from the M10 block. Even the Mclaren F1's S70 was developed from the M70 block. The S85/S65 are the first to be truly bespoke and with BMW's desire to save costs, I believe they would like to return to that traditional formula as they have done with the S63/tu. With all the rumors flying about the V6, I have faith that BMW will stick to the glorious I6 for the E8X generation. It is just not financially prudent to allocate the resources to make a great V6 (not to mention the backlash from the BMW enthusiast community).