Why can't I connect my iPhone to my car?

Ann got a new iPhone and it only works intermittently with her Mercedes SL. Sometimes it works, sometimes it doesn't. The dealership says to let the car "warm up" and let it acquire it. What can she do? Leo says that bluetooth is rather hit or miss sometimes, and in Mercedes, there are some issues with iPhones. Leo says that a car running CarPlay works best when you plug your phone into the USB port with the lightning cable. Then CarPlay sees your phone. That will probably work better. Also try unpairing or forgetting the phone and then re-pair it. That usually fixes any issues.