Tesla Motors has only been around for 10 years (founded 2003), and their first product didn't sell until 5 years later. I think it's safe to say that Tesla Motors is still a startup. They are a startup in an industry that measures time in decades.

Dave McClure makes a fair point that until a company works out the following three things, they're a startup, not a business.

1. What its product is,

2. Who its customers are.

3. How to make money.

So yes, a post-IPO company valued at $21B which still hasn't worked out two of those three items is still a startup in my opinion...

To me, Tesla does seem to have IPOed unusually early. The "usual route" I have in mind is that tech companies typically acquire some very significant market share before their IPO. Tesla look like they're still getting started.