"Does she need a car?"
Translation:¿Ella necesita un carro?
I think car should translate to Coche instead of Carro, since they use that more often
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.
On the red strip, where they tell you that your answer is wrong, there are two buttons on the bottom left: Report and Discuss. I'm describing where it is on the website on my iPad. Hope you can find it on yours.