That's interesting. I feel the opposite - I would volunteer because I'm the supporting cast and therefore the expendable one...

I think people would be more likely to volunteer in the life-or-death situation because they've got their priorities right there in front of them. In the car situation it's basically a matter of desiring physical possessions and people don't tend to think clearly in those sort of situations, greed tends to take over and make people jealous even of things they don't have yet...