Ask HN: Tesla never does any ads but still hogs all the limelight. Thoughts?

I was listening to a podcast today from dotnetrocks.com. The speaker mentioned Tesla never does any advertising. This made me think. This is really true. And, it made me wonder also - they are successful so far with getting the word out without spending a dime on marketing. This may not work for lot of companies. What do you think is help them here?

1. Elon Musk Brand 2. Superior product 3. Cult like following from consumers