Back in the truck, Max seems relieved to be finally on his way…
... until the truck sputters and dies.
Furiosa catches up with him and tells them she's installed kill switches, so no one can drive it but her. Dummy.
Max tells her that she can get in, but Furiosa wont leave without the women.
So Max weighs his options. He decides they can just wait for Immortan Joe to show up, and maybe he'll set Max free in exchange for returning his breeders.
Furiosa points out that Max is "relying on the gratitude of a very bad man," who probably won't be all that happy that Max shot at—and lightly wounded—his pregnant breeder.
Max weighs his options—or lack thereof—once more, and decides to throw in his lot with Furiosa and the women. He lets them back into the cab, all while holding a gun to Furiosa, and she continues driving again.
As they drive away, we cut back to Nux, who's left alone in the desert. He takes off at a run and manages to catch up with the War Rig. He jumps on and hides himself.
Back in the cab, Max collects all the guns and weapons so that the women can't get the drop on him.