[ReadTheLicense]

Yes! The same way, using CNG or bio-diesel (for example wood or algae-derived) in plug-in hybrid vehicles with smaller batteries (50 km) would be much more ecological than large battery vehicles.

[marcinzm]

Would they be more efficient? Burning gas is horribly inefficient and has engines have weight as well.

[ReadTheLicense]

The conversion might not be as efficient but all cars having a 350km battery for the rare occasion when they leave the city 2-3 times a month seems like a bigger waste. They would normally use the 50km battery and the lesser efficiency would kick in only during long distance trips. Modern range extenders can be pretty lightweight... It could even be modular/take-out in your frunk.

[weq]

They are more efficent because they last longer then current battery tech. China has miles of graveyards of green energy veichles. they are environmental hazzards after their useful life and run off rare earth minerals. not sustainable in any sense of the word; other then being an alternative source of fuel.