The mileage is

It's stored on the computer on the car, can't be changed. The odometer is I believe just to display it. It's completely different from the mechanical type. The tax collector reads you odometer every year then tax you according to the mileage you have driven since last time the mileage reading was taken, also tax you according to the size of your car.

That's what I could think how it's going to be done.