As Uber is a major investor in self-driving tech, self driving short term rentals are all but inevitable, and likely to become the normal way cars are used. You

As Uber is a major investor in self-driving tech, self driving short term rentals are all but inevitable, and likely to become the normal way cars are used. You can rent the whole car or pay less by car pooling, managed by an app. Probably it still will never be as energy efficient as a train on rails, but it's a lot better than one car one rider. And unlike the train, it can easily drop one rider off anywhere along the way. Or combine the two: turn trains into land ferries where the route allows, and drive road cars onto train cars on one end and off on the other.