i meant a fetus is not just a human with a bunch of parts missing. there are other differences to go with that, like being way smaller and needing another person's body to survive.
edit: for example, a fetus isn't just an adult's legs, while in the post, the "truck fetus" is the equivalent of that
i dont see how the adult pickup truck wouldn't be a fully built one, since real children aren't considered fully developed human beings
plus the pickup truck could be called elderly when it's parts aren't working as well.