How can you call yourself a carjacker if you’re deterred by something as lame as a hose? It’s called “holding your breath,” and it’s what you do so you don’t inhale water and die. Pretty easy life skill you can learn in about <1 second if you half-put your mind to it, although judging from this video these carjackers couldn’t handle it even if they put their whole mind to the task.
Tl;dr: buy a snorkel if/when you’re trying to steal cars at carwashes.