car destruction setup problem

[drawer14]

if you followed the tutorial probably you did create Tyflow for skinning which will act like bones the car mesh will be skinned to, the other meshes will be represented with a convex shapes in PhysX ( in PhyX operator check Display Hull checkbox) so when you add windows and they are attached in one mesh object, Physx will create a collision shape all around them not each window separately

this might happen even with the objects added one by one as convex shapes of the car might collide with them at frame 0 , add Physx bind and they will be in place.

Also make sure the actor object is placed exactly in the object pivot position