Physx to collide with voxels

[dv2000]

Hi,
I turned a car to voxels like lego car. I need a car to slowly fall apart after hitting walls, etc. 
I can turn some voxels to green physx shapes but I cannot add my red voxels as collision mesh that way green voxels wont go through red mesh.  What shall I do? 

2. How can bind some legos when they break only on z axis since all pieces are single pieces and the stack one into another ?

Thanks

[tyFlow]

Add a PhysX Shape to your red voxels, then using a PhysX Switch operator, convert them to kinematic. Once ready to turn green, use a PhysX Switch to turn them dynamic.