The problem with current gen Lithiums is the need for each cell (or couple cells) to have a safety chip that ensures proper charge/discharge and monitors the temp. That makes the systems rather expensive, BUT all sorts of fresh technology is being rolled out, mostly the nano-scale stuff that totally eliminates the thermal runaway and venting with flame (exploding) issues. New chemistry for the electrodes also offers greater capacity and longevity, so within a couple years I think there will be mass-market ready Lithium packs.
Toyota is using a Lithium pack in the Japanese Yaris with start/stop, so to me that means they are doing shake-down tests on them to see if they are suitable, so I fully expect to see some Lithium EV/hybrid in North America in a few years.
Cost is a big factor as well... Maybe the new Lead-Acid-Foam battery will break Lithium by offering NiMH capacity at half the price?
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