I have two fun stories about floods:
many years ago I was driving an old MGB roadster and approached a ford in a village which looked a bit deep - I went in gently and decided that it wouldn't make it - so I reversed out and turned around... days pre-sat nav, so I sat in my car with the roof down (sunny day) to look at a map...
a few minutes later the noise of a fast car approaching from the other side of the ford, a sort of hissing noise and then silence... I turned around and looked up - a modern convertible Saab (also roof down!) was sitting in the middle of the ford, water over its bonnet, with a faint steam rising from around it... the chap driving stood up in the driver's seat looked at my wet tyre marks as I had driven back out of the ford, and yelled at me: "If you could get that old thing through, how come mine didn't make it!"
*
in 2007 there were lots of floods across the Cotswolds, I had then an old range rover and had been driving it through the floods quite happily and had popped over to friends to help them with their flooded house... for entertainment I then parked it up on a local small bridge over the Thames (quite small river at this point - where the road the other side had flooded for about 1/2 a mile - historically they were water meadows either side designed to flood...) to watch local traffic... three fun interactions:
Brand new Land Rover Discovery turned up - couple in their mid 40s smartly dressed - the chap driving put the window down and asked me what his chances were of getting through - I told him: your car will have no problem, how confident are you at driving through water? he answered - about 8/10 whereupon his wife leaned over and hissed at him: 2 out of 10, 2 out of 10! They turned around and went another way...
Then a brand new range rover turned up smartly dressed chap in his 50s with young teenage son next to him - very similar conversation, but in response to being asked his confidence, he simply pressed some buttons, the car lifted up another inch or so and he confidently drove through...
Finally a BMW x5 with a group aiming to get to a wedding up north... again, the same conversation, but the reply this time was: well it is a 4x4, no point owning it if it can only cope with puddles... and he drove off into the flood and around the corner...
an hour or so later, getting bored, I went home and as I gently drove through the floods and around the first corner - there was the BMW x5 - completely stuck, engine totally dead. It turns out that the engine air intake is at the same level as the spoiler at the front bottom of the car (amazed it even copes with puddles!), so it had hoovered up the water and hydro-locked the engine - one dead engine, one dead car. The owner had phoned BMW assist, but couldn't give them a postcode and his answer of 'just over the Thames, between two fields and in a flood was apparently not accurate enough for recovery to come out to him... They kept asking him to press the BMW assist button on the dashboard, but for some reason no electronics were working in the car! So I towed him back to my house - he left the keys for BMW assist to collect the car later that week, and I dropped them all back into town to pick up a hire car (and go a different route to the wedding!)
amusing stories, but neatly sum up confidence / ability / car's capability... there is no one answer fits all scenarios - but in the right car with the right knowledge, it is surprising how much water you can drive through...