I think many of us tend to think in terms of a fully-submerged vehicle.

Here in Phoenix last month, just after a heavy rain, a pickup made a left turn at an intersection (albeit, going too fast for conditions), hydroplaned and turned over in "only" knee-deep water adjacent to the street. Two kids among the occupants.

The brief story is here.

Coincidentally, Channel Five photographers happened to be at the intersection, and caught it on film

Take a minute and watch the "Flood Video: Kids Trapped in Overturned Truck" (on the same page) to witness the near-panic and frustration as citizen-rescuers were initially unable to break out a window (thankfully, they eventually were successful). A simple tool, such as what's been mentioned here, would've been useful.

Remember, this is "only" knee-deep water.