There are a few things you can do to stay warm in your car in the winter camping. First, make sure your car has a heater. Second, put some blankets or sleeping bags on the inside of your car. Third, put a thermos of hot coffee or tea inside your car. Fourth, keep an extra set of clothes and gloves in your car for when it snows outside. Fifth, bring a heavy coat or jacket if it is cold outside. Sixth, be prepared to spend time outside if the weather is cold and snowy outside your vehicle.