As we reported last week, there have been whispers for a while that BMW's new tri-turbo 3.0-litre straight-six diesel will be dropped into an M-treated 5-series.
Now, BMW's global marketing manager for M cars, Brian Watts, has all-but-confirmed the car's existence, telling The Detroit Bureau that the project is 'under consideration' but hasn't been confirmed.
As for the nitty-gritty of the car, while nothing's confirmed there, we expect a power output in the region of 400bhp, with torque of up to 650lb ft.
This heavy torque output could mean that BMW plumps for four-wheel drive, a theory that is backed up by the M550dX moniker spotted in our previous story.
So, a four-wheel-drive diesel M car, eh? Sacrilege or a step forward? We'll let you decide that one (and we suspect you'll have a lot to say about it)...