As stated by ADAC, winter jackets impair the functionality of seat belts, which can lead to injuries in a crash. A crash test simulating a collision of two cars (one car rear-ending another) at a speed of 16 km/h showed that at the moment of impact, the belts tighten sharply and "hit" the internal organs, particularly the intestines, liver, and spleen. This is because they initially do not fit tightly to the driver's and passengers' bodies due to the extra space "filled" by winter clothing.
German experts in no way question the usefulness of seat belts – they must be fastened to minimize serious injuries in a crash. However, while in the car, it is worth giving up the winter jacket, or at least, let the seat belt be under it (by unzipping the clothing). The point is that the seat belt should be tightly stretched across the hip area, firmly pressing the person to the seat.
If it is very cold in the cabin, the car can be pre-heated, and it is also a good idea to bring a blanket.
