What is the Best way you have found to treat car doors for sound ??

- I was wondering should I just treat the car door as if it is a regular home speaker enclosure .... trying to make it as solid as I can using some kind of CLD treatments
and then adding some kind of foam to absorb the sound bouncing around inside the door???


- or just do the normal treatments you see on YouTube?

--- What are the best ways that you have found to treat car doors for sound???