"Does she need a car?"
Translation:¿Ella necesita un carro?
Both should be accepted by Dúo, because both are used a lot in different parts of the Spanish-speaking world (along with a few other words for "car").
To get "coche" accepted, use the Report button to suggest that your answer be marked correct. Eventually it will be added to the database.
It's the correct English translation rather than a literal word for word translation. Eg. We would probably not say 'She needs a car?' or if we did, it would be incredibly informal or in response to something. It's like dropping 'Yo' or 'Tú' from sentences where the verb conjugation implies who is the subject. We would not say 'Want a coffee' in English but 'Quiero un café' is perfectly acceptable in Spanish.