Thanks for the link, Silvestris.
Neal Bortz was talking about this last Friday. Privacy is a huge issue. Also it was indicated that Uncle Sam is concerned about the viability of electric vehicles that wouldn't pay a gasoline tax. A ton of issues to be sorted through though, ie: were you driving on a state highway, county road or city street, etc.
The thought makes me cringe.
"The joy of living is his, who has the heart to demand it." Teddy Roosevelt