[Ryland]

my car would have issue with the relays because they are open to the air and about 12" off the ground, the batteries and motor would be fine for a while unless it was really dirty or salty water, so basically you would ge water coming in around your feet before the car would die and even then it should limp home.
if you had sealed contactors and controllers, or had them up away from the floor, and the water is low enough that it doesn't get in the vent holes at the top of the battery then you should be fine for short trips in water, but really, who drives in rivers? if you live in a flood plane then get a row boat or move to higher ground.