Great thread!

May I just add that If you are washing your car, you can limit the negative impact of nearly all the chemical treatments you use by driving your car onto the lawn for the process. The biological process occurring in a functioning soil system is enough to detoxify most all of your commercial products.

The real problem with any washing is when it gets dumped straight into a sewer/river system. The concentration is such that what may be a relatively benign chemical is quite destructive because of the concentration.