Hi,
I got something similar last year, I asked my detailer for some advice and he told me to use a product called ecoclean delete from a company called IGL Coatings, it worked wonders: it is formulated to “eat” the stain (the words of my detailer, not mine ahaha) thanks to its very high acidity.
Here is where to buy it:
https://www.lazada.com.my/products/e...4__10001098__1
This being said, urban rain is usually very high in iron so you might want to try an iron remover too... I am not too sure about the effectiveness but if everything else fails that could be your last resort.
It is a Malaysian company hence they are on this website and not on amazon, sorry ahaha!
Anyways, if you so choose to use it get back to me and tell me if it worked as well as when I used it!