Shemeska said:More appropriate to your body would be having your car on top of a machine that collects all the water from that rain, filters it and then continually rewashes your car with that filtered water to remove the junk on your car. Eventually it will need some more water, but it'll do its job fine on the average amount it has already. Adding continually more water will just make the waste water on the other end of the filter (urine in your body) more dilute each time. The concentration of junk in your bloodstream won't change any real amount.
Eh, this is why I normally talk about lemon juice. Sweet, sweet lemon juice. I don't drink much water now that doesn't have lemon juice in it.