Just to provide a counter point, in my experience, the biggest problem I face in winter weather is other drivers. I know when I hit a patch of black ice and have difficulty stopping that the oversized van behind me is going to have more difficulty stopping, and I have the instinct to quickly turn instead of waiting on the red light. I also know that cars have difficulty stopping on a steep hill and I may wait before going through an intersection. Both of these experiences have happened in the past year for me.

This may seem like a straw-man argument, I don't intend it to be. I think self-driving cars will be on the whole better drivers, but these are also situations that I see as being extremely difficult for a computer to identify to the level a human driver is capable of.