Three forms of capital
A vehicle does not lose its value in one event. Its capacity to provide mobility, its recoverable components and its materials each have a different future, and a lifecycle system has to preserve the highest one that remains viable.
Part 3 argued that a vehicle contains several technical clocks. Its structure, propulsion, electronics, software and interior do not become obsolete at the same time. That observation changes the question that follows. When a vehicle is no longer the right unit to keep in service, what exactly has been exhausted?
The conventional answer is often the vehicle itself: it is sold, written off or treated as waste. A lifecycle system needs a more precise answer. It has to distinguish the capacity to provide mobility from the components that may still work, and both from the materials that may still be recovered.
This is not an argument for keeping every car alive indefinitely. It is an argument for deciding deliberately where productive value can still do the most work.