General Motors Co's OnStar may be watching your moves later this year -- even if you no longer subscribe to the service.

OnStar, known for connecting drivers to live operators who can provide directions or summon emergency help after an accident, starting in December plans to collect data from people who discontinue the service unless they specifically ask for the connection to be severed.

Among the details that would still be collected are speed, location and other data from global positioning system satellites, raising potential concerns from privacy advocates.

The data collected may be shared with or sold to third parties for any purpose after identifying tags are removed, the OnStar policy states. Such uses might include research into public safety or traffic services, according to the policy.

We have never sold any personally identifiable information to any third party, Joanne Finnorn, vice president for subscriber services at OnStar, said in a statement.

GM started notifying customers by email at the end of last week that it would make the changes to its privacy policies for OnStar, which is a subscription service that costs $19 or $29 per month, OnStar spokesman Adam Denison said.

Customers canceling the service will be notified that GM maintains a two-way connection and asked whether they would permit that to continue, Denison said. If the customers decline, GM would begin the process of disconnecting the vehicle immediately, he said.

GM argues that leaving the connection open would allow it to provide car owners with updated warranty or recall data and warn of severe weather conditions.