CollectionService is perfect for that. You can tag the green parts with an identifier, then get an array of all those tagged parts in the game using the GetTagged method.
I like this plugin for assigning tags in studio without needing to set them from code.
Edit: You dont have to manually make your FilterList array this way; you can retrieve it right from GetTagged():
-- assumes the green parts are tagged with "CarDeckWeld"
local FilterList = CollectionService:GetTagged("CarDeckWeld")