About one in five cars on American roadways connects to outside parties via cellular telephone networks, transmitting data on drivers' speeding and braking habits, their location, and their vehicle's health and performance. By 2025, AAA predicts, all new cars will.

Computers on board most vehicles on the road already collect and monitor such data, which can be downloaded at dealerships for repair purposes and shared with manufacturers, who say it's used to make cars safer and more reliable.

But civil liberties and driver advocacy organizations — including those in Maryland — are becoming concerned about how secure such data is, who has access to it and whether it may drive up repair costs. AAA Mid-Atlantic has identified the growth of so-called "connected cars" as the next big thing on its policy agenda in the state.

Much of the data collected by today's "computers on wheels" is capable of revealing "not only where you live and where you work, but where you drink and who your friends and lovers are, and where you worship," said Jay Stanley, a senior policy analyst with the American Civil Liberties Union. "It raises a lot of questions about who controls that data and who gets access to it."

Such questions come as drivers are connecting every day with more and more devices and apps that promise convenience on the road, industry observers say.

E-ZPass lets drivers move quickly through toll booths. Insurance companies — including AAA — offer discounted rates for drivers willing to use devices capable of transmitting data on their driving habits. The National Highway Traffic Safety Administration has pushed the use of "black boxes," which record driving data in the moments before an accident to enhance crash investigations and improve safety.

General Motors' OnStar and other such vehicular information systems provide a range of services, from crash notification and navigation to hands-free access to phones and email. They also can connect to a growing array of applications for everything from finding parking or a Starbucks to connecting to Facebook.

On its website, OnStar acknowledged that it collects a wide variety of information about its users and their vehicles, including their location and speed. It said it keeps the data as long as it wants and may use it "for any purpose or share it with any third party if we anonymize it so that it no longer reasonably identifies you or your vehicle."

Driver information can be shared with emergency service providers, with GM, with OnStar service providers and any third party with a legal request, according to its policy. Account and vehicle-related information can be shared with GM to "enable it to evaluate or research the safety, quality, usage, and functionality of its vehicles" or with third parties for "joint marketing initiatives."

AAA appreciates how the data can improve safety but would like to see more transparency from manufacturers about what is being collected and how it is shared, and more control over that data in the hands of vehicle owners, said Bernhard M. Koch, CEO of AAA Mid-Atlantic.

The driver advocacy group has yet to start crafting potential legislation in Maryland, he said, but wants to start a conversation about drivers' rights to privacy and access to the data.

"Consumers need to know what their cars know about them," said Nate Cardozo, a staff attorney with the Electronic Frontier Foundation, which defends civil liberties "in the digital world."

He warned it's "just a matter of time" before a data breach occurs with data collected by auto manufacturers. When it does, drivers won't know what personal information has been compromised because automakers don't disclose what they collect, he said.

Automakers have fought efforts in other states to force more data transparency, arguing that sharing too much information on their systems would only make them vulnerable.

Dan Gage, a spokesman for the Alliance of Automobile Manufacturers, said legislation on the issue now would be "premature," in part because "the last thing we want to do is restrict driving innovation."

The debate sets the stage for a lobbying battle in Annapolis and at the federal level in coming years as normally allied power brokers in the auto industry clash.

AAA boasts more than 50 million members nationwide and routinely sees its policy recommendations receive serious attention from legislators, though it has only spent about $800,000 on federal lobbying since 2013, according to OpenSecrets.org.

Gage's auto alliance, which says it represents General Motors and 11 other manufacturers responsible for more than three quarters of all car and light truck sales in the United States, has spent nearly $10 million on federal lobbying since 2013 and it isn't shying away from the data fight.

"If AAA is proposing policy changes, or proposing legislation in any state, we would be very, very interested," Gage said. "It's very important that automakers have a very early and direct role in the development of that policy."

The issue isn't new. The Maryland Transportation Authority has been blocked for years from sharing drivers' E-ZPass data with anyone except the account holder, his or her attorney, contractors who need to access the data as part of the system's operations, and those who file valid subpoenas for the data. The agency generally only keeps data for two years, said spokeswoman Rebecca Freeberger.