Roadster? A coast-to-coast autonomous drive? Hover mode? Tesla is teasing some big dreams, but still hasn't delivered on the last ones. Elon Musk visited the Tesla Design Studio over the weekend.

Tesla CEO Elon Musk pushed back the dates for a demo of the next-gen Tesla Roadster, which he has said will be able to “fly” and suggested that it might not even be a car at all. Tesla has been ...