Jesus rail

n.

The passenger hand rail above the car window. Used by people who can't drive, those who prefer to be in control, or frightened mothers.

(in car, Driver accelerates)

Passenger: Jesus! (holding onto car hand rail for dear life)
Driver: You don't have to hold onto the Jesus rail, I'm doing the speed limit!

Passenger: (holding onto car hand rail, eyes closed)
Driver: Stop holding the Jesus rail, I'm not trying to kill you!

etc.