Although electric and plug-in hybrid vehicles have been considered the only plausible alternatives to conventional cars for a long time, and practically all of the world’s biggest car makers have been investing heavily in these technologies, and governments around the world have been trying to promote the use of such vehicles by offering generous incentives and financial benefits to those who choose to buy an alternative fuel vehicle instead of a gasoline-powered car, adoption has been lagging and sales have not been as strong as the auto industry had expected.