People who have suffered a clash with a vehicle (such as pedestrians or passengers in a vehicle), in most cases do not know, what was happening prior to the clash. The medicine calls this state amnesia.
Based on the experience with having read through more than a thousand testimonies in practice, it can be said that this state is so frequent that it is rather an exception, if a person actually can recollect the entire incident realistically even after having experienced it. The last moments prior to the collision can not be recollected by most of the wounded (and sometimes not even by people who have not been hurt).