The car does not pick up the OK google (or OK siri) through the car audio. Your PHONE needs to hear you. I use the "Hey Siri" feature on my iPhone to send and read text messages in my tesla. I was used to being able to do this with my previous BMWs. In the BMW you could access the phone itself by LONG pressing the voice activation button (short press = cars system, long press = phone itself).
Doesnt work that way in tesla, so begrudgingly I setup Hey Siri so that I could duplicate what I had in my BMW as far as listening to text messages and responding, while keeping both hands on wheel and eyes on road.
I couple this use with my Apple watch, by ensuring that my iPhone screen is off so that notifications are sent to my watch. That way, if someone sends a text, I get a notification (vibration) on my watch, I can say "Hey siri... read my last text message" and the phone will hear me, and activate through the cars speakers (showing the "in call" icons that appear when you make a call using the cars interface), and read my text message to me through the cars speakers.
My phone sits on a wireless charging pad (nomad) that I bought, in the spot where the regular non wireless pad comes by default. I have the cubby where the phone sits open, to ensure the phone can hear me.
Ensure that your "OK google" works outside the car, then put the phone in the car, on the spot where the phone dock is. Ensure that the door is OPEN and then try saying OK google while you are at rest and not going anywhere to ensue the phone can hear you while you are not going anywhere / with no media on.
The only mistake you are making is thinking that the cars microphones currently pick up your "Ok google" and send it to the phone. From what I can tell, unfortunately it does not currently work that way so I developed the work flow I mentioned above for this purpose.
Maybe they change it at some point? One of the beauties of this car is that they absolutely could activate a long press for activating the microphones on the car if they wanted to, I am fairly certain.
