Id never ever use a gas station wash on my car knowing the kind of shit I wash off my truck with the brushes, ive been asked to leave and not come back at the Millbay Shell because I clogged the drain with mud and rocks.
And yeah, if your car is dark colored good luck keeping it clean, my car is dark blue and usually lasts about 2 days before its covered in wet leafs, cedar/alder tree gunk or if its dry out the hatch is covered in dust. Actually if it even just gets frosty overnight my car is covered in dust when it thaws out, damn salt/sand shit on the roads.
next car I get is going to be silver, I swear.