Where do these cars rust?

[Hamster]

So, looks like the best way to prevent rust is to keep it clean, I guess. I've been running my car through an automatic touchless car wash in the winter, so it looks like I'll keep doing it. Automatic touchless carwashes are expensive, $10 around where I live for the full wash, including undercarriage. But getting rust cut out and the panel repainted would cost a lot more, so I shouldn't complain. Silly question, but would driving your car during a heavy rainstorm clean out the fender lips? Or would it actually cause more dirt to accumulate?

I haven't gotten any of the corrosion on the wiper arms that people here are talking about. Maybe I'm just lucky.