I drove a Hyundai that wanted to sync contacts from my phone when I connected it to Bluetooth to play music. I declined for privacy reasons, and the car then had this loud booming audio request to sync contacts every single time I turned on the car and then I had to wait 30 seconds for the car to timeout/fail after my phone denied the request, and then I had to click on a touchscreen to skip the sync rather than retry.

I ended up just not using Bluetooth while I drove that car because it was such a nuisance. I'm not sure whether it was so bad because of incompetence (they never considered users not wanting to share contacts) or out of malice (they know they can wear people down through harassment and hassle to eventually share their data).