In my experience in only makes alloy wheels.
I think its the same for everything.
Upgrade to white seats - only produces white seats.
Upgrade to heated steering wheels - only produces that type.
I pretty much keep my production lines segregated by car class.
All the base models have base features.
So i can manufacture wheels next to this line.
Model 2’s all have five point wheels.
I have to import all those.
Model 3’s all have alloy wheels.
So i can manufacture alloy next to this line.
It seems the import conveyors have trouble filling spots when the same line switches back and forth, between, regular wheels, alloy, black etc.
They only way I have found to combat this is to build atleast 5 of the same car in a row. Then switch models. It seems to make the delays “somewhat” less per line.