Try going from having bluetooth off on your phone to bluetooth being on in your car that has bluetooth capable device. It sucks. Every car I've been has trouble

Try going from having bluetooth off on your phone to bluetooth being on in your car that has bluetooth capable device. It sucks. Every car I've been has trouble pairing if bluetooth wasn't on prior to me entering the car. For one car, I had to turn the engine off for it pair. WTF?