No privacy for you!
With the proliferation of hybrid vehicles, California's roadways face a looming funding crisis. As more people drive longer distances on less gasoline, less money will be available through the gas tax to deal with road wear and tear. The California Performance Review floats the notion of a mileage tax to make up for lost revenue. It would require surveillance of some sort to monitor the miles covered by every individual's vehicle.
I'd like to see them try. Californians will go apeshit.