It's not bad but a waste of time.

May get struck by lightening. Plus it is a complete waste of time to wash it in the rain.

1) No, it could be a good idea. The main advantage is that the rain is doing the rinsing. If the rain is very strong, you won't even need soaping, just let the rain do all the work. Only stay in the rain if it is not dangerous: mind the lightnings and don't catch a cold. It is certainly more fun if it is not too cold. Don't drive on dirty roads afterwards. This could ruin your work. 2) "Yeah, I've done this lots of times... if its a warm summer day, its kinda fun to be out in the rain actually... Fun part aside, it does make a lot of sense. Although rainwater is not 100 percent pure, its certainly better than hosewater, and less likely to cause waterspots... So, if youre just looking for an OK in-between wash, a rain-rinse is a good way to go..." "it's highly unlikely that you will become a lighting rod, since you'll probably be next to an object that is quite a bit taller than you (like your house or apt). Now if you're some how washing it in in a clear empty field, then you are just asking for it." "Well I’m not going to start washing my car in the rain, but I thought the reason cars spotted up after a rain shower is because they were dirty. It’s not that the rain water is dirty. Also, waterspots occur due to the fact that the water is drying on the car, not hand dried." "ive done that once. i had to wash the car so i could apply a proper layer of wax before heading up to the snow. it was great until the neighbors started to ask me thousands of questions. "dont you know it's raining?" "why are you washing your car in the rain?" "it's raining you know?" " "I've done it a few times, its fun if its not too cold outside. It won't leave any spots if you dry it right when the rain stops. The spots aren't from crap in the water, they are from other dust in the air when things start drying and the dust settles on your car before the rain drops evaporate." "I still think thats a bad idea. Even while its raining and you apply the soap to it, it will rinse it off, which is ok. And the rain won't let it dry on there. I agree with that too. But the rain will still be hitting the ground next to the car, splashing little dirt droplets all over the bottom side. I think you need to still put soap on it right after to make sure you aren't spreading all the little dirt particles accumulated on the bottom all over the side of the car. But that's just me. I guess I like my car to look the best it can, and not just buff the dirt in the best I can." Source and further information: http://forums.nasioc.com/forums/showthread.php?t=1072315 Further information: - "My new car is dirty and its raining. should I wash the car or will the rain clean it. ?" http://answers.yahoo.com/question/index?qid=20090123172517AAn1fN3

I don't know, I've never seen a car raining.

4-22-2017 It's a waste of effort. Every drop of rain water holds a speck of dust, so you have to wash it again no matter what.

No, and it could help if it's very dirty. I'd rather have a few water spots than bird droppings on it or vomit streaking out the window.