I've been beating this drum about self-driving cars for a while. All these rosy predictions of traffic being better neglect the fact that usage will go way up.
The car could have a "unoccupied miles driven counter" that you reported manually or automatically once in a while. Much like how you report your electricity usage to the power company.
In 2045: “What do you mean you are going to DMV? You work there? WAIT. Are you still hand-steering that 2025 Prius!? And you still haven’t fixed that yanked off telematics!?”