
The car's unofficial name refers to Nazi Germany's state-operated leisure organisation "Strength Through Joy". So in War Boy culture, it is misremembered (perhaps deliberately) as Freude durch Kraft, or "Joy By Force". Which certainly seems more appropriate in this context.
A high-up source confirmed this, and that "War Boy dyslexia" allows it to be read as "fucked", which is a pretty reasonable description of the car after its run-in with the War Rig!