After Sen. Al Franken (D-Minn.) pressed Ford to clarify its use of GPS tracking in vehicles, the automaker sent him a letter about its privacy practices on Wednesday.

Jim Farley, Ford's executive vice-president of global marketing and sales, said at CES in January that the company's GPS system allows it to "know everyone who breaks the law." In response, Franken, who often focuses on privacy issues, asked Ford for clarification on its privacy practices.

Franken's letter came on the heels of a U.S. Government Accountability Office report that found car companies need clearer privacy policies when it comes to handling consumer data produced by in-car navigation systems.

Ford replied to Franken's questions, saying it "is absolutely committed to protecting our customers’ privacy."

"No location data is wirelessly transmitted from the vehicle without customer consent," Curt Magleby, vice-president of U.S. governmental affairs, wrote in his letter. "Location data is used only to support customer requests for services, and to troubleshoot and improve our products."

However, Magleby added that the company does retain some data, and has shared it with law-enforcement agencies on certain occasions.

In response to a question about whether Ford requires a warrant to share location data with government or law-enforcement agencies, Magleby wrote, "Ford receives court orders on behalf of law enforcement or individuals involved in litigation to retrieve and provide data from various vehicle modules. Such data is retrieved with direct physical access to the vehicle, and on rare occasions, has included location information."

All Ford cars sold in 2013 and 2014 are equipped with a navigation system that stores "latitude, longitude and a timestamp" for two to three weeks, Magleby wrote.

His letter revealed that Ford shares customer data with 24/7, Inrix and MyAssist, third-party service providers that the company uses to provide Sync Services, a subscription service that customers access for turn-by-turn directions, business searches and traffic updates. For other services, customers have to opt in to allow Ford to collect data or transmit it to a third party.

Ford also shares location data with Acquity Group, a digital-marketing company, whenever a customer uses MyFord Mobile, an app for plug-in hybrids or electric cars.

"GPS information, travel direction, and vehicle speed may be transmitted," Magleby wrote. "Vehicle speed is only transmitted under certain circumstances, such as when the electric-battery charge is low. Ford and our service provider retain personally identifiable location data for 90 days."