[Growler]

August, some states don't perform annual inspections, but that doesn't really matter, either.

In Maryland, all drivers on vehicles not otherwise waived (historic, or above a certain age, mostly) participate in the Vehicle Emissions Inspection Program (VEIP) every other year, meaning two years between tests. Mileage is recorded at that time. For taxation purposes, it would not be a great stretch to take the last two VEIP mileage readings, average them, and bill half annually as tax.

If they're going to tax driving miles, those funds should be solely for maintenance of road infrastructure, though; city/state-based mass transit could perhaps benefit as well, both with increased ridership (people don't want another tax burden) and some financial benefit from the tax itself. What I wouldn't want to see is that mileage tax going into, say, a new stadium project. But when have we ever enjoyed having a direct say in the employment of our taxes?