They have been doing it in Canada for quite some time.On one of my heliskiing trips to British Columbia we rented a car and drove to the middle of BC.A few weeks later the guy that had his name on the rental recieved at speeding ticket.He wasn't even driving.
I have one of those mobile units on a street near me.For some reason I drive real fast up to it to see how high I can get it.Seems to work backwards in my case.