It could be reported each time the car is serviced or at registration time. Seems to happen in the US like that sometimes.

If people misreport it, it would be caught when they try to sell the vehicle. Eg, if I report 5K per year, but actually do 20K, then if I try to sell it in 5 years time, and it shows 25K on the Registration info, but 100K on the odo, then I'm not buying that car lol

But, of course, they'll go for the "track your car at all times" option. An app that you must operate and sends real time GPS info would be their wet dream. Or they could just take the Maps data you send directly from Apple and Google lol

As an aside, insurance companies would love this too. You were speeding by 3km/h? Your insurance premium has just jumped by 20%.

I wondered about this also, FWIW my solution would be self reporting verified at the time of vehicle sale or end of vehicle life. I believe some states require periodic roadworthy checks which would also be an opportunity for verification.

Real time vehicle tracking is obviously unacceptable.

Have you heard of toolbooths?

There are variations that require neither self reporting nor tracking cars. Grab a ticket uppon entering the highway. Feed the ticket in the exit booth and pay with cash or credit card. The machine uses the ticket to compute the distance.