In the GS manual, lookup VEC_TO_MESH.
VEC_TO_MESH is intended for deforming models and terrain in real time, infact the example code for that function is a code that puts a dent into a model by moving a single vertex inward by 10%.
I suppose you would get a crushed-in effect by causing the vertices at wherever the collision occurs to "match" the vertex positions of the wall you run into until your windshield comes close to the wall itself.
