When the question is not a negative question the response for the given question should be: Q: ¿Tienes carro? "Sí, tengo." for a positive answer or "No tengo." for a negative one. No, what if ...
I've read that one should use "ir a" when time of completion is certain. If the time is uncertain, one should use the future tense. This choice is not so clear-cut when asking a question. Take for ...