I was drinking a glass of Perier and I was reminded of the fact that soda water is excellent for lifting stains out of clothing, so would it be advantageous to wash a car with it? Unorthodox, and perhaps a stupid question, but I wonder if those little bubbles are good at stripping off grime without doing any harm.
I know of a few who use soda water to neutralise bird droppings on the paint - I would worry about the salt(sodium) in the water causing marks in the paint
Club soda has minerals (salt), but there are seltzer waters and sparkling waters without any minerals. Also, I have come across it for close to $1 a gallon which is not too expensive if you are using it sparingly on your prized automobile. I am just curious if it is effective, and or if it would affect the lsp