It depends on the climate that you live in and the time of the year, but one suggestion that I make for most climates is to start with a sleeping bag (not a blanket) and water as the root (everyone already has auto chargers for their cellphone right?).
In a place like the southeast, a cotton sheet and a mosquito head cover (and water) is the root for summer nights, in the desert, lots of water, sleeping bag and a couple of reflective "survival blankets" with twine to cover your car roof is the root.
If you live in very cold places and you don't already have a 72 hour kit (which can be very involved for places that drop below 20 degrees, then you really need to start visiting survival threads, breaking down at 20 below zero, wearing sneakers, bluejeans, and having a stylish jacket draped over the seat takes some real preparation to survive, even for a night if your heater isn't working.
Thanks for answering about the 72 hour kit.
Even Fema is encouraging preparedness these days. Disasters happen all the time, we have been lulled into complacency and laziness. We automatically jump into our cars in the morning and expect the world to be the same today as it was yesterday.
guess what?
it won’t!
YOU are responsible for your own safety and well-being.