Skepticism is good for you...
I have to admit that I am not sure what you were after here.
Anyway,whether the story about a woman of size X lifting a car of size Z is true or not is not the case,there´s no doubt that someone could "push" their limits under such a situation,there are limits to it though (telling you something you do not know?)
It has to be kept in mind that tales,stories and "urban legends" pop up all the time,they may also grow in size as they get passed on.Such stories are seldom infallible.