Australia's cities are growing at a massive rate, but the space for those new residents to live in is limited. It basically doesn't exist beyond high-rise apartment blocks, at least within metropolitan areas. And that means that owning a car won't be possible -- isn't possible now -- for a lot of people. That's where car-sharing comes in. And Sydney is one of the world's most car-sharing friendly cities, according to a new report that suggests up to 10,000 fewer cars are being driven within the CBD bounds with those cars replaced by less than a thousand car-sharing vehicles.