[elviejo]

Investor != Cofounder.

Cofounder is someone that is there from day 1. Tesla Roadster existed before Musks's involvement. Martin Eberheard searched for Ventura Capital, one of his leads was Elon Musk.

See my other reply for the links.

[joey89y]

Tesla was really started by a small company called AC propulsion. They made the prototype roadster. Elon and Martin both approached AC separately to take the car to Mass Market but they wern't interested, so Elon and Martin teamed up. Elon financed the company and Martin ran it. However in 2008, after a series of massive mistakes, Elon had to recap the company with every penny he had and Martin was fired.

Lesson is. Corporate history is a lot like hotdogs. They have equal claim co-founder status.