Links to some interesting articles about electric cars and other "green" vehicles:
Electric vs. gasoline efficiency.
Best achievable energy efficiency of a car with an internal-combustion engine.
Until 1924: low-polluting steam cars, "Stanley Steamer" and several other types.
Since XIX Century until now: Electric cars -- low polution, very high fuel economy, and... disapointingly short range.
Hybrid vehicles, in general.
Plug-in hybrids -- a frontrunner in the "green-car community"?
Nissan Leaf owner's opinion
EXTRAS:
Fuel cells.
Fuel cell vehicles.
External combustion: The famous Stirling Engine
Applications of the Stirling Engine.