What is the best liquid detergent for washing your car?

Hi! I personally use Simple Green on my van. I have used it for years. You can even clean carpets with it. It makes tires cleaner than any carwash detergent I have ever used. Plus, its concentrated, so just a little in a bucket of water is all you need. I spray it undiluted on the tires and rims tho. Also, its harmless to the environment!