@relevante so I jabe a rwd S P85 and live near Green Bay.
When the roads are slick the regen will try to kick in, cause the rear to lose traction, cut regen, regain traction then try and go normal regen..........it can't react fast as ABS and is not a "smart" system. On those days you need to switch to low regen once it is safe to play with the screen.
Maybe awd regen works better, I had a S 85D as a loaner last fall and while I drove in slush it was not all that slick. Oddly I will say the front felt like it was scrambling for traction and I prefer the feel of my rwd car, though I am sure past a few inches of snow the AWD is better.
Heading into my 4th winter I don't have a problem with how it all works. I have gotten better about preemptively switching to low, and the cold battery limits regen a lot too