Still possible to section the recovered material and analyse the microstructure. No problem for a decent metallurgy lab. Doubt VW will be inclined to share the results though...look out for recalls...
Entirely depends on how well the sites survived though, and you need the cause not the effect of course. Looking again, outer rim will be best bet. will likely just be a fecking great pothole induced fracture though, no surprises.
I've seen my fair share of metallurgical examinations as a turbine engineer, we have a metallurgy lab on site. Capture the tip my man always tells us!