Three Senators have raised concerns about an announcement by GM's OnStar's subsidiary that it would continue collecting data from customers' cars even after they cancelled their OnStar service. In a Wednesday letter to the company, Al Franken (D-MN) and Chris Coons (D-DE) warned that "OnStar's actions appear to violate basic principles of privacy and fairness."

On Sunday, Sen. Chuck Schumer (D-NY) raised objections of his own. He released a letter he has written to the Federal Trade Commission seeking an investigation of OnStar's privacy practices. Schumer described OnStar's new policy as "one of the most brazen invasions of privacy in recent memory."

OnStar is apparently hoping to create a new revenue stream by collecting data about the movements of OnStar-equipped cars. Obviously, this data set will be more comprehensive—and, therefore, more lucrative—if it includes data from former OnStar subscribers as well as current ones. In an announcement e-mailed to subscribers earlier this month, the company said that, starting December 1, it would continue collecting data from subscribers even after they cancel their service. OnStar also said it reserved the right to sell aggregated and anonymized data to third parties.

In an interview with the New York Times last week, an OnStar spokesman defended the policy, noting that former customers can opt out of data collection. But Franken and Coons say this isn't good enough. For example, they point out that OnStar forces customers to opt out by phone; there's no online option.

They also express skepticism about OnStar's anonymization promise. They point to the "broad body of research showing that it is extraordinarily difficult to successfully anonymize highly personal data like location."

Franken and Coons call for Congress to "enact privacy laws that protect private, sensitive information like location." Franken has sponsored legislation that would do just that.