HTC One Bluetooth Carsound too low

[Jesper67]

My HTC one connects fine with the bluetooth in my car and the function works fine. But when I make a call the sound is much to low. Driving at slow pace I can barely hear the words and neither the volume control in the car nor in the phone solves the problem. My car worked fine with my previous phones ranging from iPhone, Galaxy S3 to HTC 8x.

Any ideas.