My setup doesn't really change in the winter, except for snowtires, snow scrapper and brushes and when i'm going abroad snowchains (snowchains are illegal to use in my country).

From memory; so i probably forgetting things:

For road side issues:
- Trifold shovel
- Traxion plates (very effective and less messy then gritt)
- Towstrap
- Jumpercables
- LED flares 4x
- Flashlights
- gloves
- multitool
- Hi-viz vests 5x
- Warning triangle 2x

Spare parts:
- Fuses
- Light bulbs
- Plugs and tools
- valve cores and tool
- wire
- Zipties
- Spare batteries (AA and AAA)
(also spare tire, jack, tire iron)

Little survival kit:
- Trangia mess kit as container/cooking vessel
- Esbit stove
- Emergency blanket
- Whistle
- Mirror
- Waterbag
- purification tablets
- Lighter and matches
- Manual chain saw
- Small knife
- candles
- 72 hours lifeboard ration (not in the mess kit, but stored in the same bag)

Randomly put:
- Blanket
- Pillow
- Waterbottles
- Hand sanitizer
- toilet paper