I think this is a new advisory. When I picked up my permit two weeks ago, the ranger advised that water bottles should not be visible in the car. Apparently the bears now associate water bottles with the presence of food, and the sight of the bottles could provoke a break-in. (The under the car approach might address that issue though.)
Yep. Two weekends ago a ranger swept the parking lot at the Portal and posted notices on (or cited) about one car in three for food violations. Several people were warned based on the presence of just one visible water bottle left on a console beverage rack. Apparently a tougher response to the activities of the two extraordinarily troublesome bears this summer. They even give you a spiel about these particular bears at the IA Center when picking up your permit.
On the sleeping-in-vehicles question, yes it's done often - almost a ritual for many. However, I heard Amy at the store tell two different people who asked the same question that, no, it is not allowed. After the second one, I asked her about it. She said the INFS has asked that the store discourage people from doing so, although they know it happens every day. She mentioned that very occassionally a Forest Service employee will make rounds late at night looking for auto-sleepers outside the campgrounds. This was news to me. Anyone have any experience with this?
