1. Weight of vehicle + total annual miles driven — regardless of whether a vehicle is gasoline or electric powered (or both).
Will the tracking system needed for such a system be an “invasion of privacy”?
But it’s a lot fairer to plug-in drivers than a flat-fee/tax system, a system which singles out plug-in owners and penalizes them for driving cleaner, usually smaller/lighter cars. Equally frustrating: A flat tax/fee system fails to reward those who drive fewer miles and who own lighter vehicles which are clearly less destructive to the American transportation infrastructure than heavier vehicles.