Car speed data can identify where you have driven

Researchers have found that GPS technology is not needed to show where a driver travelled - a starting point and the car's speed are enough.
Rutgers University scientists have demonstrated that even without a GPS device or other location-sensing technology, where a driver travelled can be shown with no more information than a starting location and a steady stream of data that shows how fast the person was driving.
Speed data collected by some insurance companies could compromise a customer's privacy, researchers said.
Drivers who avoid jackrabbit starts and sudden stops are typically lower-risk drivers, and insurance companies benefit by rewarding such behaviour.

So some insurance companies are offering lower premiums to customers who install a device that constantly measures, records and reports their speed.
"The companies claim this doesn't compromise privacy, because all they are collecting is your speed, not your location," said Janne Lindqvist, assistant professor in the Department of Electrical and Computer Engineering at Rutgers.

"But we've shown that speed data and a starting point are all we need to roughly identify where you have driven," Lindqvist added.
Reproducing an exact driving path from this limited and basic information is challenging - and it is less precise than using GPS or cellular signal tracking measurements.

But with the researchers' approach, sometimes even one drive is enough to reveal the person's destination within a third of a mile or less.
The technique, dubbed "elastic pathing", predicts pathways by seeing how speed patterns match street layouts.
To test how well the elastic pathing technique worked, Lindqvist and his colleagues examined data from six drivers in New Jersey travelling to 46 different destinations over 240 trips, and from 21 drivers in Seattle over 691 trips.
For more than 20 per cent of the trips, the technique predicted the final destination within a little less than one-third of a mile from the actual endpoint.

Lindqvist doesn't claim that insurance companies are actually processing the data to reveal locations. The techniques he and his colleagues are exploring are in their early stages and are not obvious to implement.
Insurance companies likely wouldn't benefit from knowing this information, especially if it is costly to obtain.
But, he believes, it's conceivable that law enforcement agencies could subpoena this information and run these kinds of complex analyses if they want to find out where someone has driven.