Electric cars are great but I think it all depends on how you are creating the electricity to power the cars. If you are creating the electricity from a big company who are burning loads of fossil fuels? Are you really using the car to the best of its abilities?
Is it more or less sustainable than a normally petrol car?
But if you were powering your car from solar power, biomass, wind power or water power that is obviously better for the environment.
Bellow how much Co2 admissions does it have to be before you can call it 'green'? Well around one litre of petrol produces roughly 2.4kg of Co2 and you can go about 10km (6.2 miles) with that, so I would say as long as one litre produces less than 1kg of Co2.
I have so many ideas of new all-electric cars and know that there are people all over the world trying to create sustainable cars and we can already see the progress with all-electric, driverless cars!