If you want to charge by miles driven, why not just require that you report your mileage each year when you renew the vehicle license plates? Yes some people will cheat but if you make the penalty severe enough, say take away the plates for six month for a first offence, twelve for a second, I wonder how many will risk it? Enforcement could include odometer checks whenever a vehicle is stopped for a traffic infraction, mandatory reporting of odometer readings by all licensed garages or whenever a title is transferred, spot checks when vehicle license plates are renewed etc.

I'm puzzled why the concern about paying for miles travelled out of state comes up so often. Do they scowl at out of state licensed cars that aren't helping to pay for road maintenance in their state?