It would not be beneficial to standardize such s young technology. It is likely that the best car battery design hasn't been invented yet. Standards bodies are there to codify best practices and not to decide things by themselves.
There's no reason to dictate the battery chemistry or internal cell layout. As long as a standard is set for slow-ish charging (i.e.: the battery tells the charger, "give me X amps at Y volts"), we're good to go.