Saving time does not equal an increase in productivity. Self-driving cars might save 20 minutes, but this translates into an increase in actual worker productiv

Saving time does not equal an increase in productivity. Self-driving cars might save 20 minutes, but this translates into an increase in actual worker productivity (causing an increase in GDP) only if those 20 minutes can then be spent doing additional work that would otherwise not have happened. This requires "work that may be done" to be elastic. Elastic in this context would mean that any free 20-minute interval can be turned into profitable work output. In my experience, workload does not scale this way.