Well, I discovered something today that might help somebody.

My van was parked in the parking lot of the grocery store, and when I came out, there was a line of white paint on its side.

Fortunately, not dents or creasing. I tried to rub the paint off but that didn't work, and water didn't help. For some weird reason, I took a tube of lip balm (Open Nature beeswax lip balm) and put a little on my finger and rubbed the paint. The white paint came off really easily. I don't know if it was the beeswax or what, but it worked great.