Explain like I'm five: Dirt caking on to cars
 

For the longest time, after rain or overnight frost melt over my car would lead to this dirt forming in patterns over my car. Didn't matter if it was machine wash, touchless wash, or handwash the dirt would show as long as water touched the car and dried after looking like this

http://imgur.com/3j3h9Ez.jpg
http://m.imgur.com/b5rg6w6.jpg

Is there a solution for this, such as claybar or wax? Or is it doomed to look like this after everytime it rains?

depending where you park or how far you've driven after the wash, there is a layer of dust that will stick to the car

what you're seeing is the condensation and dew on the car or from rain that forms the water "bubbles" on the paint.

the dust mixes with these bubbles or spots, and when the water dries up, this is what is left behind.

try parking on kingsway in the summer for a day and you'll see just how much dust settles on the car - I used to rinse my car daily, that gets rid of most water and dust spots.

solution would be to use a really good wax / sealant with limited silicone, and rinse the car as often as you can

So basically theres no point in washing it at all until summer because the dirt is going to get in there and cake on regardless (either because where I'm parked or because of the almost daily rain) until I get to properly wax the thing.

By rinsing the car, you mean just with water and drying down with a microfiber cloth or complete wash with soap as well?

Yup, and with the way cars are designed these days they create all kinds of different pressure zones from the air passing over the car. You see a lot of rear bumpers get plastered with muck because of this.

Mind doing an ELI5 for what you meant?

Apologies for me being too :derp:

The aerodynamics of the car make the back dirty.

Wash, clay, polish, wax. When it gets dusty, hose it off. Wash it every week or 2.

flipturner nailed it.

I wash ever couple days. If your washing often make sure you use a quality wash mitt and make sure its clean. If not then you will end up scratching the car up very fast. I was an idiot the other day at work and thought I would wash the car real quick with the wash brush there.....needless to say, I will be polishing it again soon :P

If you guys hose it off, do you still get water marks?