Offering this line of business at a car wash baffles me. I've never needed a bag of ice and said to myself "I'll just head up to the local car wash and grab a bag", nor have any of my customers asked me for it. However, perhaps in my area it's not the norm, in other areas it might be. I can see if your near a lake where a lot of boaters come through, or other recreation events where customers are in need of ice, then perhaps so. What I'm saying is, if there is a need, go for it. If you're trying to create demand, I scratch my head.