Automobile door and door pillar assembly preventing detachment of door during collision

In an assembly of an automobile door and a hollow pillar which hingedly holds the door, the improvement comprising at least one protuberance of a generally vertical ridge shape formed on an edge face of said door opposite an end face of said pillar, the cross-sectional profile of said protuberance defining an apex and two sides, said two sides making an acute angle at said apex, and at least one rigid reinforcing member attached to said pillar, said protuberance and said reinforcing member being shaped and arranged in such a correlated manner that said protuberance is apart from said reinforcing member in the closed door state and that said protuberance comes into engagement with said end face of said pillar in confirmance with the cross-sectional profile of said reinforcing member when said door in the closed state is forced to collide with said pillar by an impulsive force in the longitudinal direction of the door in a collision of the automobile, so that said door is prevented from being laterally detached from said pillar, wherein said reinforcing member is disposed in the interior space of said pillar, and the cross-sectional profile of said reinforcing member is generally similar to the cross-sectional profile of said pillar in the same horizontal plane over a major portion of the periphery thereof and locally differentiated such that a portion of said space at a region opposite said protuberance is left unfilled with said reinforcing member, said protuberance and said reinforcing member being shaped and arranged in such a correlated manner that said protuberance dents said end face of said pillar at a region defining the unfilled space in accordance with the differentiated profile of said reinforcing member and engages with the dented region when said door in the closed state is forced to collide with said pillar.