I've done a fair amount of research (like here), but I can't find any examples of hyphen rules with "auto". Microsoft Word doesn't take "autopopulate", but will accept either auto-populate or auto populate.
What I read about prefixes is that they shouldn't be hyphenated, but MS Word disagrees with this one. Unless auto isn't really a prefix at all, but I do take it to be.
Right now I'm thinking that auto doesn't usually work by itself unless you're talking about a car.
Does anybody have any authoritative word or grammatical insight?