On or about May 1, 2009, Elon Musk, the Silicon Valley entrepreneur and CEO of the electric car maker Tesla Motors, fired off an angry email to me regarding a story I had written in the pages of my then-employer.

I no longer have these emails, but as I recall, at issue was my public skepticism that a car such as the Model S could be built, within the technical specifications Mr. Musk laid out, before the end of 2012.

After many years writing about the car business, I have come to appreciate how difficult it is for an established manufacturer to build any car, even a conventional automobile relying on incumbent technologies.

Mr. Musk's Model S was a radically different automotive vision -- a premium sedan with an all-electric powertrain, potential seven-passenger seating, and a battery back that would serve as a stressed, that is, a load-bearing member of the chassis, and yet would be easily removed and replaced. That such a car should come in three years from a company that at the time didn't even have an assembly hall seemed an impossible boast.

Mr. Musk then bet me $1 million that he would do it and, graciously acknowledging our rather different financial situations – he's wealthy and I'm not – said the bet would be only $1,000 to me. In either case, he wrote, the winnings would go to the charity Doctors Without Borders. Seeing this as a rare opportunity to facilitate a $1 million donation to a worthy cause, I accepted.