Tesla: Better Warranty? Check! Upgradeable Cars? Sure! 500-Mile Batteries? Maybe Soon!

Leave it to Tesla Motors to turn what could have been a rather dull announcement about improving its service program into something of a mini-dazzler Friday. CEO Elon Musk not only promised to honor the company's 8-year battery warranty under pretty much all conditions -- "lighting the pack on fire with a blowtorch is not covered" -- but Tesla also rolled out a plan that allowed owners to upgrade to a top-of-the-line Model S anytime their car goes in for service. Musk also hinted that today's 26...