I found it was possible to remove from vicinity inventory but I had to stand in weird positions like; at the back of the car to remove the engine parts, and on top of the car to remove front wheels/hood.

I got the suggestion from a reddit thread reporting the same issue. If you are on PC walk around the car with inventory open and you should see the parts become selectable. I'm playing on xbox, where you cant move whilst inventory is open, so I moved while opening and closing inventory until I could see the parts.

You might need to put the parts in your inventory, I just held X on the bigger parts to drop them to the vicinity, not sure what the equivalent action/key on PC is

The ability to aim at a ruined part and take it to hands is still bugged though :(