Vehicle Electronics and Water[1]

No big deal unless its very salt water. Most electronics will work after a soaking from fresh water.

Also depends whether the airbags deploy. If so, the airbag ECU can blow a pyro fuse on the 12V battery to disconnect the electrical system in the event of an impact. eg if you went through the crash barrier into water the airbags could blow the pyro when you hit the barrier so the car is de-powered when it hits the water.

As well as EVs and hybrids (which use pyros to de-power the HV system), a number of ICE cars have pyros now - eg Audis and BMWs.

It's a bit surprising cars don't have easily-accessible escape hammers like they do with buses and trains - eg under the seat.

Theo

But from repair videos I've seen, on ICE cars the pyro fuse tends to isolate the starter motor, rather than everything ...

No big deal given the voltage involved.

And fresh water and 12V wont blow any fuses, anyway

A few years back I gave the family "Under-the-tree" Christmas presents - you know, the little extra presents that are not the main one - of an escape hammer/USB charge socket combination. The idea is that it's always available because it's plugged into the 12v accessory socket formerly known as the cigar lighter socket. It's not a long hammery-shaped thing but a hold-in-the-palm-of-your-hand heavy mass with a glass-breaking point on the end. None of them have been tested in real life, I'm pleased to say.

Nick