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Still not clear. GPS can work without a SIM. Is the device logging locally when the SIM is not activated or not?

If it is then we have a concealed tracking device that can be used against the interests of the car owner at any time. It just happened that EFF didn't have the know-how to extract the logs.

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Great question, and yes, some of the better devices implement a small buffer so may be able to keep a day or even two in memory while they're out of cell coverage. If you activate the SIM you might get a small data dump.

GPS doesn't need a SIM, and indeed the devices will have a fix all the time whether activated or not. They do require cell service to send their updates anywhere. They're all simple GPS receivers, not transmitters, thus require an active SIM.

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