"GM captured minuted details such as station selection, volume level, and ZIP codes of vehicle owners, and then used the car’s built-in Wi-Fi signal to upload the data to its servers. The goal was to determine the relationship between what drivers listen to and what they buy and then turn around and sell the data to advertisers and radio operators."

https://www.theverge.com/2018/10/17/17990052/gm-radio-listen-tracking-habits-advertising-future