By installing tracking devices on your car and charging you per mile. They're already on it.
As is more or less necessary. Gas taxes are the primary source of money for road construction and maintenance. But the wear and tear on the roads is proportionate to the number of miles driven, not to the fuel used to propel the vehicle.
So at present electric vehicles are essentially driving for free on roads paid for by those driving ICE vehicles.
Being able to track millions of citizens as they go about their business is a wet dream for Big Brother Obama. This just gets their foot in the door. They will eventually expand this to put a tracking device in EVERY car.