Might add here that police have since revised the timeline, claiming he wasn't on the phone with a dispatcher for 45 minutes...it was more like 3.5 minutes before the line cut out according to them.
As for breaking a window, fair few newer cars now come with laminated front side windows and dang near all cars here downunder has some kind of tint applied. So even if you can shatter the window it might still stick together.
And sadly this kind of thing happens every time we have a flood, this one would be #1 out of 3 this time around (3rd still haven't been found but her car turned up as the water started going down).