this occurs when automotive components, such as the engine transmission suspension and wheels, are forced into the front passenger compartment of a vehicle during an accident. In some older vehicles, there can be a great deal of intrusion causing serious injury. This occurs more often in offset collisions with another car or a fixed object such as a tree or guardrail., footwell - recess in the floor below the feet of the rear seat occupants, but may also be used for the space used by the feet of people in the front seats