Your additional data is never sent to Google’s servers. The entire map is built in JS, so once you have loaded the Gmap scripts, there is no need to send data.
You can check this in the browser’s developer console: no additional AJAX request will be made to Google as soon as the first map display is complete.
If you use the geocoding or routes service (and possibly other services, but I never used them), you need to send addresses or LatLng to Google via AJAX for calculation.
source share