Don't apostrophes usually denote possessive? Actually I think there are a few exception like numbers but I can't remember I'd have to look in my English writing book. I hadn't actively thought about this so I hope I'm not doing this lol. I'll pay attention and see if I do it. XD
It's true, apostrophes are used to denote possessive, but sometimes this isn't the case, such as when a word is contracted. Ex: One very common mistake (I do it a lot actually) is to write "it's" instead of "its". In that case, the possessive is in fact without an apostrophe.
"The car lost its wheel" is correct because "the car lost it's wheel" actually means "the car lost it is wheel."
Another complication is plural possessive: "My parents' house", "the dogs' owner", etc.
(I know you're probably aware of all this, I guess I'm just leaving more info here for the sake of the thread itself ^^; Bad grammar bugs me too, so I'm glad someone's talking about it XD)