Automotive News reports that BMW is looking at turbocharged motors for its M-cars. Although lower-level BMW models have sported turbochargers for some time (including the 135i and 335i), M-cars, including the M3, M5, M6, and Z4M, have, to date, avoided forced induction.
The report specifically hints that the next M5 (and logically, the M6) may shift to a twin-turbo V-8 in lieu of the current 500-hp, 5.0-liter V-10. Insiders claim the motor is based off the twin-turbo 4.4-liter V-8 found in the X6 crossover, and is reportedly capable of producing more than 536 hp.
Source: Automotive News