in(to), on(to), (up)on

Hey, I’d like to know your opinion on the prepositions listed in the subject: can it be called a rule that whenever you use one “into”, “onto” or “upon”, you might just as well use “in”, “on” or “on” respectively. After all, we can both get into and in the car. We can be onto or on it. And a movie may be based both upon and on a novel. Is it true?

It’s not true that “into” can always be replaced by “in”, nor “onto” by “on”. For a start, it’s not hard to think of phrasal verbs that don’t work with that substitution (or where the meaning completely changes, as in a couple of the examples below):

“I’m turning into my father!”
“I’m really getting into this band.”
“We’re going to move our data onto the new server.”
“I think you’re onto something!”

I’m finding it harder to think of examples where “upon” cannot be replaced by “on” with essentially unchanged meaning (though often with less formality). All I can come up with so far is the set expression “Once upon a time”. I would be surprised if there aren’t others though.

[edited] Oh… also there’s the dated exclamation “Upon my word!”, but again it’s a set expression. Perhaps the “upon” examples are limited to such? I’m not sure…