I think it is a great way to get a customers attentions since all people will carry and look at their messages immediately while it may take some time before getting to email on their computer. I have tried it a few times and noticed not only a quicker response time but it also lets me know how serious a customer really is about purchasing a vehicle. If they do not respond from this format, chances are they were only trying to get information to go elswhere to beat your deal or use it as levearage to show another dealer. I would be careful as to what you text and make it intriging enough for the customer to return the call.