In my car kit, I have a tube tent, heat sheet, 2 emergency ponchos, 3 wool blankets (laid flat, lining trunk), and an orange tarp, no lightweight tent though. I need to get to get off my butt and get some heavy plastic sheeting, as I think it would be very useful if some joker smashes my window out or if I lose a window in a crash. I think the best bet is to improve the vehicle as a shelter if necessary, but also have a fall back if the vehicle is unsafe.