WOW, never have seen that much dirt on the entire backside of a car in California.... The most we get is a light dusting of sand on the car because we don't get snow and tons of rain.....
I hate being the awful example that causes people to take unnecessary and wasteful action. My car is now clean(ish) thanks to Mother Nature. I left my car at the Amtrak station for the best part of a week while I went gallivanting on the train. While I was away, heavy rains washed away the dirt (except under the rear spoiler). Unfortunately, they also washed away some train track. Oh, well, nothing's perfect. https://www.timesargus.com/news/local/heavy-rains-cause-isolated-flooding/article_71266975-460d-5ec9-82a8-9c8d5eac69ba.html