I did that once a long, long time ago when I changed the pants I was going to wear that day and threw them in the trunk of the car ( a '79 Camaro ). About the time the trunk lid closed, it occured to me what I had done. Panic does no good at that point.

Ever since, and especially when I am in a remote place by myself, I won't close the car door until I check for my keys. Its one thing to do it when the car is in the driveway, its another thing when you are miles and miles from pavement and there is no one else around.

John