Is there a way of muting the radio while the Nav system is giving directions? My wife seems to think it used to do this but doesn't anymore. Tks!

 

The radio and sat nav use independent volume controls. Try adjusting the volume only while the sat nav is playing a message then adjust it while the radio is playing. You should find that, when the radio is on, during the playing of sat nav information, the radio volume will reduce (not mute completely) .