Limited Bluetooth functionality in car vs HTC One M8

My car used to display contacts and call logs from my previous device, the HTC One M8. I just started using my new 6P, which I love, but the functionality is significantly limited. Almost none of the controls in my car work for the 6P, and none of the above-mentioned info loads. I've checked and the setting is enabled to allow the transfer of contacts, etc. So basically all I can do is place a call FROM my phone (not from my car's screen/steering wheel) and it'll use Bluetooth. I can also hang up a phone call from my nav screen, but not the steering wheel. I know there are several threads about bluetooth connectivity, but I don't think my issue has specifically been addressed. The connection is actually fine; it's just the functionality that is at issue here. I was surprised considering I'm on a much newer device now. Does anyone have insight here? Is this most likely an issue with my car, my phone, or both? Are there any known fixes? Thank you in advance!! :)