In one classic episode of The Simpsons, Homer comes home and goes:

Who needs a carwash when you can just drive around in the rain?

It's obviously meant as an absurd joke, poking fun at Homer's low intelligence. But it always struck me as a very thought-provoking question, at least for somebody like myself who has never had a car. Maybe I'm as dumb as Homer.

I can't remember that we ever once washed the car in a professional car wash. We always just waited for the next time it rained, and then the car was automatically washed. At most, we may have used a cheap car washing sponge and a bucket of water in the summer, but I'm not sure why, since it rains soon enough anyway.

Why would anyone need to use a professional car washing service, other than in some extreme situation such as you've just driven around in the mud and completely covered your car and your boss' family is coming over for dinner in an hour and there is no rain to be expected for the entire week and you really need to make a good impression on them?

Yes, I mean this question seriously.


1 Answer 1


If you've seen a motor vehicle that has not been washed in some time, you'll note that particulates such as dust and pollen will adhere, even through a rain storm. Sometimes, the gunk will remain attached even while driving through heavy rain.

There are locations on the vehicle that are static, that is, do not experience airflow and by extension, water flow. Those locations will retain the dirt and have to be washed away by mechanical means.

The mechanical means can be a professional car wash, but if that car wash is merely brushes and forced water and soap, some locations can remain uncleaned.

Hand washing with a sponge, soap and water can be more effective, if approached carefully. One could avoid the bucket of water if one performs the wash in a torrential downpour.

  • Rain can even supply the dirt particles…
    – Solar Mike
    Aug 10, 2021 at 5:53

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