if you mean like this then i’ve tried it, i also removed some junk on the inside that will not be visible, ive joined all the bodies to one single unit except for wheels etc.
i got the same error when trying to import glb only withglb it didnt start the autosave right away and I could even place the car in the scene.
the crash occurs when the autosave kicks in or if i manually save.
i have one part of the mesh that does look quite white so im going to remove it to see if it lacks material.
I tried at an earlier stage to immport the car without the new wheels and without armature and was successful so my thoughts lean towards the armature causing problems.
at this moment im trying to rig the car without the addon as you suggested and hoping it works 
super big thanks for the support once again!