Your car, tracked: the rapid rise of license plate readers
Tiburon, a small but wealthy town just northeast of the Golden Gate Bridge, has an unusual distinction: it was one of the first towns in the country to mount automated license plate readers (LPRs) at its city borders—the only two roads going in and out of town. Effectively, that means the cops are keeping an eye on every car coming and going.
A contentious plan? Not in Tiburon, where the city council approved the cameras unanimously back in November 2009.
The scanners can read 60 license plates per second, then match observed plates against a "hot list" of wanted vehicles, stolen cars, or criminal suspects. LPRs have increasingly become a mainstay of law enforcement nationwide; many agencies tout them as a highly effective "force multiplier" for catching bad guys, most notably burglars, car thieves, child molesters, kidnappers, terrorists, and—potentially—undocumented immigrants.
Today, tens of thousands of LPRs are being used by law enforcement agencies all over the country—practically every week, local media around the country report on some LPR expansion. But the system's unchecked and largely unmonitored use raises significant privacy concerns. License plates, dates, times, and locations of all cars seen are kept in law enforcement databases for months or even years at a time. In the worst case, the New York State Police keeps all of its LPR data indefinitely. No universal standard governs how long data can or should be retained.
Not surprisingly, the expanded use of LPRs has drawn the ire of privacy watchdogs. In late July 2012, the American Civil Liberties Union and its affiliates sent requests to local police departments and state agencies across 38 states to request information on how LPRs are used.
http://arstechnica.com/tech-policy/2012/08/your-car-tracked-the-rapid-rise-of-license-plate-readers/
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Go through a toll booth, reach the next one too soon and get a speeding ticket on the spot. 
Apparently installed on some UK motorways but current doubts as to whether they are in use yet. System is designed to have a speeding offense notification ready for mail from our main licensing office in c. 20 seconds flat.
