Farhad Manjoo

Ten years ago, a little-known tech entrepreneur named Elon Musk published a secret master plan for Tesla Motors, an ambitious electric car start-up he had funded.
 Revolutionary technologies always start as impractical and expensive, Mr. Musk explained, so Tesla’s first car would be a two-seat roadster that sold for $110,000. But by plowing profits from that car into research and production capacity, Mr. Musk promised that Tesla would quickly create a series of cheaper cars in higher volumes, all toward an almost mythical aim: creating a long-range electric car that could travel more than 200 miles on a single charge, but that cost less than $40,000 for the privilege.
 This year, Mr. Musk’s white whale — a car that will get 238 miles per charge, and will sell for about $30,000 after a federal rebate — will finally make it to the roads. Mr. Musk’s master plan has gone exactly as he promised, except for one tiny hitch.