Are your really sure this is how it works even for atutomotive electronics? I am involved in the automotive industry, more in tech aspects than in comercial ones, but what I know is:

- car makers don't make their electronics. I don't know of exceptions. What they normally do is to design the architecture, the requirements and buy from Tier 1 supppliers: Bosch, Continental, Vitesco, Valeo, Delphi, Magneti Marelli etc.

- the contracts, when awarded, are multi anual and usualy specifiy the units per year during project lifetime production and in serial life (after the product is not produced, the supplier MUST GUARANTEE to be able to provide the part)

- these contracts usualy go in numbers like N million parts (ECUs) for 4-5 year total (SoP date to EoP date) + serial life for X years. Then they get detailed, even the plants where the parts are made ar negotiated. Slips on both sides come with penalty. I don't know all the details.

- lots of electronics are safety relevant (iso 26262) especially in this case, once HW design is frozen, is frozen. You cannot change silicon components easy as this will make the product undergo a long series of product and design validation which take many months => the Tier 1 supplier MUST SECURE it's own supply from chip makers.

- usual "suspects" to supply the Tier 1 are chip makers like Infineon, Renesas, NXP, STM. Probably at some point, maybe TSMC comes into the picture. There are many providers of small electronic parts.