Here’s one view. Surely some of the price of the car was for the engine cover which on purchase became the property of the car owner, not VW. They removed it because of the problem with overheating and most importantly for them, to limit liability for any damage that might occur.
Was true consent obtained for removal? Taking property without consent is often theft.
What is the collective value of the covers they physically removed and retained?
Why has there been no expedient steps to replace what they took?
Presumably, the engine cover was part of the system to lessen injury to pedestrians in the event of a collision. So, who has liability if this absence contributes to injuries?
Perhaps we should all write to VW and state that in the absence of a replacement we want our property returned.
They have our money already and we’re not important to them. Not returning the covers doesn’t cost them anything. As I said earlier their attitude to the customers whose property they removed is disdain. This is really shocking treatment that deserves to be called out. Perhaps to make amends for their appalling attitude they will provide us with carbon fibre engine covers.

Oops, there goes a flying pig!

Rant over.