Good timing Tim, I just took this picture this morning, with this thread in mind.

Both of these water bottles were in my car. I have a case in the back and the ones on the back edge froze, and the ones in the middle did not. The frozen one in the picture was actually in the door. This water has been in my car for months and this is the FIRST time I've seen them frozen. I know in the past people asked about keeping water from freezing in the vehicle. Looks like it's not as big of a problem as one might assume; however I will say that the frozen bottle from the picture is sitting on my counter now, and is still about 60% ice as it wasn't very warm today, or in my house.