PALO ALTO -- There are many ways to measure Tesla Motors (TSLA)'
remarkable progress in the three years since the electric-
carmaker launched its initial public offering. There's the
first-ever profitable quarter this spring. There's the nearly
perfect 99 out of 100 score in Consumer Reports' review of the
Model S sedan. There's the stock price, up more than 500 percent
since June 2010 and currently trading around $99.55 a share.
Then there's this: Tesla, which is on track to build 21,000 cars
at its Fremont factory this year, is worth more than Fiat and
nearly a quarter as much as General Motors -- which has 21,000
dealers.  In a considerable understatement, Tesla CEO Elon Musk
told shareholders this month: "This has been a great year.
Things have really gone pretty well. ... I'm having a lot more
fun these days."  But while Tesla has proved it can make an
expensive electric car, it has not yet met its goal of making an
affordable one, and its long-term success may hinge on its
ability to drive down battery