When a car moves...
When a car accelerates, which direction will our body move? And why? Answer: Remember Inertia?
Since you have mass, you will naturally have inertia: the tendency to resist change. Hence, when the car accelerates, from rest or constant velocity, there will be a time period where you body will resist this movement - hence, the car will move faster than your body, the seat pushing you forward, creating the impression that you are moving backwards.
