Any member had issues with their windows on their z12 on cold, very cold weather. Lowering very very slowly, and getting way up so slowly that at some moment, it seem to take a pause?
Had a SpecV in the past and never had this kind of trouble. But with my z12, gosh it sucks.

Troubles start at the -15C (5F) range and colder.

It might be an actual defect with your car. I know with my locks on my 3 when it's really cold, it sounds like it's having some trouble. No one else is reporting the problem so I went in to have it fixed and they switched out the motor, free of charge.

Might be. Actually, it's always when I'm getting in/out the parking lot of my job that the problem occur with my driver window since I must pass a magnetic car to get in/out of it.
Other point, the driver window is the only one with the feature to get down/up automatically while pressing on the buttom, and on cold weather, I must leave my finger on it.

I,ll check that with my car dealer.

Got any pics of your Cube? Care to share?