I know a couple of car dealers that have vacant back lots as big as football stadiums.
In 2019 they were packed to the gills.
That is primarily because of the chip shortages. The auto manufacturers have huge lots filled with assembled vehicles that lack the chips to control the electronics. Any shortage in aluminum will probably not be felt for quite a while in the auto market, as the manufacturers will have a big backlog of vehicles waiting for chips for quite some time. You will start seeing reductions in vehicle production simply because they will run out of room and money to keep storing partially finished vehicles...