I'm not an expert by any means, these are just some of my thoughts.<br><br>Water is obviously the most important thing not only for survival, but just for day to day functioning, so since I'm never very far away from my car (as some who have posted are, so their situations may be different) I keep half a case of bottled water in the trunk to supplement the bottle I carry in my backpack. <br>Living just outside of Washington DC, the terrorist attacks changed the way I thought about survival. I used to envision scenarios that could happen while I was backpacking or canoeing, but now I think about what could happen going to and from work and school. A couple people have mentioned smoke and gasses as potential dangers. I could smell the Pentagon burning from my house, and ever since then an asbestos mask (home depot, $5) has been in my backpack and in my car. <br>On a slightly less dark note, I'm supprised that I haven't seen anyone mention gas siphons. the only times I have ever run out of gas were when either there were no gas stations around, or the one that was there was closed for the day. Maybe that's just my luck, but it seems Murphy's laws are always at work, so the next day I bought a length of plastic tubing and a gas can that stay in the trunk. <br> Once again, I don't claim to be an expert, these are just some of my thoughts.