A Northeastern University study, conducted with Consumer Reports, watched 21 late-model vehicles and 30 companion apps to see who was receiving driver data.
The answer includes some of the largest advertising companies in the world.
Inside the Tent The study, titled Automatic Transmission: An Empirical Study of Data Privacy in the Connected Vehicle Ecosystem, is peer-reviewed and is being published this week.
Several told Consumer Reports that drivers agree to data sharing when they register and sign in, which puts the responsibility on the customer.
Consumer Reports has published a guide to opting out of driver-behavior data sharing and requesting deletion, though opting out may cost some convenience features.