Tesla Motors gets a $465 million taxpayer loan. Why?

Why does Tesla Motors, the ambitious Silicon Valley electric car company, need a $465 million taxpayer loan if it can raise hundreds of millions of dollars from private interests? Its latest round was a cool $82.5 million from a private investor group led by Fjord Capital Management.

"It was an opportunistic investment," Elon Musk, the former Paypal honcho and CEO of Silicon Valley-based Tesla told Bloomberg on Tuesday at the Frankfurt Motor Show.

"We were not looking for money," Musk said. Indeed. The Department of Energy just approved a $465 million taxpayer loan to Tesla as part of the federal government's green tech stimulus. The loan will apparently be doled out to Tesla on an "as needed" basis. But why?