Global automakers are feeding real-time location information and dozens of other data points from electric vehicles to Chinese government monitoring centres, potentially adding to China's rich kit of surveillance tools as President Xi Jinping steps up the use of technology to track Chinese citizens.
Generally, it happens without car owners' knowledge, The Associated Press found.
More than 200 automakers selling electric vehicles in China - including Tesla, Volkswagen, BMW, Daimler, Ford, General Motors, Nissan, Mitsubishi and US-listed start-up NIO - send at least 61 data points to government-backed monitoring platforms, under rules published in 2016.
Automakers say they are merely complying with local laws, which apply only to alternative energy vehicles. Chinese officials say the data is used for analytics to improve public safety, facilitate industrial development and infrastructure planning, and to prevent fraud in subsidy programs.
But critics say the information collected exceeds those goals and could be used to undermine foreign carmakers' competitive position, or for surveillance. Under Xi's leadership, China has unleashed a war on dissent, marshalling big data and artificial intelligence to create a more perfect kind of policing that can quickly neutralise perceived threats to the stability of the ruling Communist Party.
There is also concern about the precedent these rules set for sharing data from next-generation connected cars, which may soon transmit even more personal information.
"You're learning a lot about people's day-to-day activities and that becomes part of what I call ubiquitous surveillance," said Michael Chertoff, who was secretary of the Department of Homeland Security under President George W. Bush and wrote a book called Exploding Data.
"Companies have to ask themselves, 'Is this really something we want to do in terms of our corporate values, even if it means otherwise forgoing that market?'"
At the Shanghai Electric Vehicle Public Data Collecting, Monitoring and Research Center, a wall-sized screen glows with dots. Each represents one of more than 222,000 vehicles connected to the system, coursing along Shanghai's roads to create a massive real-time map that could reveal where people live, shop, work, and worship.
Data also flows to a national monitoring center run by the Beijing Institute of Technology, which pulls information from more than 1.1 million new energy vehicles. Those numbers are about to get much bigger, as Beijing pushes electric vehicle development as part of its "Made in China 2025" industrial development plan.
Ding Xiaohua, the deputy director of the Shanghai centre, said monitoring is not designed to facilitate state surveillance, though data can be shared with police, prosecutors or courts, if a formal request is made. The centre is registered as a non-profit but is tightly aligned with and funded by the government.
There is a privacy firewall built into the system. The data center has each car's unique vehicle identification number, but to link that with the owner's personal details, it must go through the automaker - a step it has taken in the past. Chinese law enforcement can also link the vehicle identification number with the owner's personal information.
"To speak bluntly, the government doesn't need to surveil through a platform like ours," Ding said.
Many vehicles in the US, Europe and Japan transmit position information back to automakers, who feed it to car-tracking apps, maps that pinpoint nearby amenities and emergency services providers. But the data stops there. Government or law enforcement agencies would generally only be able to access vehicle data in the context of a specific criminal investigation and in the US would typically need a court order, lawyers said.
Automakers initially resisted sharing information with the Shanghai monitoring centre; then the government made transmitting data a prerequisite for getting incentives.