It is a good idea to keep blankets in the car. We keep two in each truck, along with emergency packs.
In those packs are a couple of pairs of socks for each of us, some gloves, long johns and first aid kits.
We live near the mountains and if we were to break down during the winter months. We could stay warm until helps arrives. Also the cell phone is in my purse for emergencies.
The blankets we have in the trucks are twin size made from a fleece material.