Seldom used? Even New York City has lots of cars.

I think people are assuming everyone else is just like them.

As for universal car-sharing, it starts with the idea that "cars are idle 90% of the time" and ignores the fact that 80% of people want to use them at the same time: on their morning and evening commutes.

http://en.wikipedia.org/wiki/List_of_U.S._cities_with_most_h...

It would appear that many people do live without cars so there is an untapped market.

This is why cars will never disappear. The solution is self-driving cars. Cars are a menace when operated by humans. Reducing the danger, traffic problems, and parking issue with cars is the answer, not removing them entirely (although I do support banning them in dense urban areas and business districts -- people can always park on the outskirts and take transit in).

But yes, cars are necessary sometimes. We need a solution for people who only need a car a couple of times a month or less. A fleet of self driving cars you can rent perhaps? Like a taxi service without the driver.