Hum...after reading all this I have come to the conclusion that the bypass is a gimick, not really required unless you are in a situation like, say New Orleans or live in Florida where the potential for lots of water does happen. But it would have to be half way up your tire depending on how low your car is in which case your interior could be all wet too. And I would be driving out of, not into the water if I was driving at all...and very slowly too. Nice example though.

 

You never know man. I live in Vegas and it hardly rains here but there are big posted sign by the government about flooding. A few inches over the average could cause a flood here since the drainage system of the city is not designed to handle heavy rain.