Leave something in the tank

A metaphor with many different versions e.g. ‘nothing left in the tank’, ‘little left in the tank’ etc, which mean that reserves or supplies of almost anything - stamina, nerve, fortitude, skill etc, are diminished or almost diminished. The allusion of course is having enough fuel in the tank of an automobile to reach one’s goal or destination and the metaphor dates from the early 20th century.