There’s an xkcd cartoon popular among copy-editors because it combines fussiness over hyphens with gently risqué humour:
Language Log, meeting language lovers’ most niche desires and then some, has a bibliography of suffixal –ass as an intensive modifier. In this vein, you’d expect the hyphen in little ass car to go between the first two words unless you were being seedy, or xkcdy. But there’s an exception, and it’s not rude at all.
Irish author Pádraic Ó Conaire, in his short story collection Field and Fair (Mercier Press, 1966; tr. Cormac Breathnach), refers several times to his ass-car, by which he means his donkey and cart. One story, about how the author came to befriend the donkey, is titled ‘My Little Black Ass’. It’s hard to read that now and not find alternative meanings rubbing up against the intended one.