It's a totally morbid thought, but I've spent more time this morning trying to figure if you'd have any chance at survival/how'd you die in a situation like this. Would the impact with the water shatter the windows/windshield so you'd have a chance to escape if you survived the fall? If not would your car just slowly fill with water? Is it deep enough the pressure would eventually break your windshield?
Just awful, pit-in-your-stomach type things to think about. But it's the exact reason I always breath a sigh of relief when I'm fully across a bridge.