On a list of things to do if ever kidnapped and put into a car trunk is to kick out the tail light and stick your hand/arm outside and wave. Driver can't see this but other drivers can and can get help.
That is, if your legs are free.
Good idea.
Here in Kalistan a woman locked in a trunk tore off a bit of liner and wrote "HELP" on it and was able to slide it out the edge of the trunk lid.
It was seen.
She was rescued.
And a number of kidnap/rape/murders were solved...