[LeifCarrotson]

> you don't keep the production lines for spare parts around for another 20 years

As a controls engineer who supports a number of automotive manufacturing lines, this is not accurate. They're still running many of those production lines, just at lower volumes, or just shuttled to less important locations. They may eventually transition to alternative (more manual) production methods, and yeah, some new-old-stock exists, but they don't stop after 5 years.

In particular, I loathe the lines where they used polyurethane moisture-cure hot-melt adhesive. It's awesome for bonding wood veneers to plastics, and it's not a huge deal when you're in production running 2 or 3 shifts weekdays and one on weekends (it somewhat reacts with itself and cleans out the lines), but even when the supplier buys the expensive purge compound from Nordsen and purges it after they run the line for one shift a month, the next time they go to start it up after sitting idle and cold, something's going to be plugged up.

When you sell equipment to an automotive manufacturer, you have to design it for a service life of at least 10 years. And they'll use it for every one of those, and they'll hold you to it.