I'm looking at the present, i think there are millions of cars....and come to think about this, if all this cars will be using electric with a rechargable batteries lets say Li-On, and it takes lots of Li-On rechargable batteries (usually occupies all floorings of the car) to run a single or double seater car. And Li-On only last for maybe 3 yrs. So we will be dumping TONS of Lithium i think everyday if all the world use it.
It's the waste actually, that discourages me when i design a motocross scooter. I have made one and test it for friend commercial use, its really fun, jumping and flying and acrobats..... but my maong pants is always destroyed by the acid coming from the Lead Acid battery. Thats when realize that battery is not good its toxic.