duolingo keeps suggesting correct translations of "a car" as "coche" in stead of "un coche"; what´s up with that? literally it says: "... does not have car". Is it common slang, or official grammar? Is it only applicable to car, or only in negative sentences?
If you say "un coche" might mean that she has not only a single one, but instead it might be that she has none or several cars, so it is better to use "no tiene coche" instead "no tiene un coche".
Lol I wouldn't recommend it. It would sound very strange and unless they knew a good amount of English, the wouldn't understand it. You could try though! Check out the looks you get :)