Ever since the debut of the Chevy Volt concept in January 2007, some people have been wondering about Toyota's attitude toward plug-in vehicles. This situation was not helped by some negative comments by Toyota executives in fall 2007 denigrating the concept of a extended range EV. Toyota has since shown some prototype plug-in hybrid Priuses and committed to offering a plug-in version of the next gen Prius starting in late 2009. Nonetheless, Toyota has also said repeatedly that the company doesn't feel that lithium batteries are ready yet for prime time in the mass market. On the company's Open Road blog today, VP Communications, Irv Miller reiterates Toyota's commitment to building plug-in hybrids. Toyota will start regular assembly line production of lithium ion batteries at its Panasonic EV joint venture later in 2009 to supply the initial volumes PHEV Priuses. Miller makes clear that Toyota is going slow with initial production in order to ensure the reliability of the packs, something which remains a big question mark for automotive applications. Companies like GM are moving aggressively to do accelerated testing of lithium batteries, but until significant quantities are being used in real world applications, there is no way to know for sure if the testing is accurate. The other issue as Miller describes it, is understanding how drivers will use PHEVs in the real world. This is necessary to make sure that they build the right kind of car with the right capabilities.