An anonymous reader writes: As Tesla finally delivered its first production model of the all-electric Roadster this month, researchers from the big automakers and their outsourced startup labs are hitting stride in the development of cheap, high-powered lithium-ion batteries that will actually end up in our garages. Toyota, in fact, says it's got enough of the chemistry down to roll out a test fleet for the plug-in Prius before the end of 2009. It's mass production of battery tech that's the holdup—which might mean Mercedes electric hybrids beat the Prius to market en masse by 2010 or 2011. From the article: "There doesn't seem to be a clear winner here or a one-size-fits-all solution. 'The chemical makeup will, in part, depend on application,' says Dave Vieau, CEO of battery supplier A123 Systems. 'One type of lithium-ion might be better for use in hybrids, while another is better for plug-ins.'"