This should have been very clear from the beginning. Battery technology is not even near what it needs to be to be cost effective. The best technology I’ve read about involved carbon fiber fly wheels to store energy but the federal government snapped that up and it is now used almost exclusively in satellites. There is still some fly wheel usage being considered by car manufacturers but primarily as a kinetic energy recovery mechanism. The beauty of flywheels is that they can “charge” spin up in a fraction of the time that a battery can charge and they can also store as much as 10 times the energy of a typical chemical battery using a fraction of the space. The only other near term option is fuel cell tech which appears to have floundered. Most green technology involving cars sadly at this point is more of a scam than anything of real import. There are very few situations where a gasline powered vehicle can not be more economically and ecologically friendly than an equivalent “green” vehicle.
http://powerpulse.net/story.php?storyID=15286
http://reviews.cnet.com/8301-13746_7-20068342-48.html
Formula One cars use some type of “kinetic energy” recovery system.
I’d be curious about your thoughts and if you can tell us how they work and for what purpose.