Well, I'm looking for the system to be voice activated, rather than a kludge of manual and hands-free activities. I'm in the process of preparing from feedback to the Google's Android Auto team describing the enhancements that would make it more user friendly.Turn off the radio by pressing/holding the volume button, put a destination in Waze or Google Maps and adjust it's volume while it's giving you the turn-by-turn directions.
There appears to be 3 different volumes within the Bolt:Examining the volume control further, the Android Auto related sounds appear to have two categories: "audio" for the level of sounds originating from Android apps on connected phone. These are two distinct settings, and you can only adjust them with the Bolt's physical volume controls (knob on the dash or +/- buttons on the back of the steering wheel) while the sound you're hearing is from the particular one of those two sources that you want to adjust. It does appear that the volume levels of "audio" and "voice" persist when you next "boot up" your Bolt. I still need to do a bit more testing. Assuming this is the case, then the Google Assistant needs to learn how to accept voice commands for "hey google set voice volume to xx percent" and "hey google set audio volume to yy percent" -- and perhaps simply "hey google set volume to vv percent" for setting both types of sound to vv percent. Then there's the volume from the Bolt's built-in head unit's FM and XM radio (or from connected USB media), which I'm guessing is what you change when you select a radio station and then adjust that volume. Not sure what that one is "called" on the LCD screen's volume indicator that shows up as you adjust the volume. Comments/corrections appreciated!
If you're using Google Maps then there's an option in its Settings menu (which you can access from your standalone phone when it's not connected to the car) to choose low, medium or high volume for spoken directions.Is there a way to change the volume (raise/lower) of the GPS when using Android Auto without changing the radio's volume?