About the ending (big spoiler alert)
It's my opinion that ever resourceful Max did jump in the back of the trash chewing truck, as a back up plan, in case, Noodles backed out of shooting him.
Max wanted out of his scandal in the most dignified way possible, before investigations and eventual indictment began, and his murder was the only way. Suicide would have left his legacy tarnished, family in more scandal, and not protected by life insurance.
So, Noodles shows up, declines to help Max, Max goes to plan B with truck awaiting at curb, and, as he came in Noodles life jumping off the back of a truck, leaves Noodles' life jumping back on.
This way his disappearance (death) looks like a kind of possible kidnapping, he's never found, eventually declared dead, and insurance pays.
"If Mad Max Fury Road is an 8 (I gave it a 1). Then I'll use 8 for OK, 9 is better, 10 is best."