In addition to a flat road tax, Plug-In America also thinks a tax based on the vehicle miles traveled plus weight should be considered, and that a suite of incentives -- both financial and nonfinancial -- should be enacted to spur EV adoption.

CNN: New taxes make electric vehicle owners pay their share

In very related news, GM has struck a deal with Massachusetts-based battery developer A123 Systems to produce flat lithium-ion batteries for use in upcoming plug-in electric vehicles, such as the Chevy Volt.

ENGADGET: Toyota delays next-gen Prius while GM inks deal with lithium-ion maker