If it becomes popular to share cars then this may work. Looking at reality I have my doubts though. If people wanted to share cars you would see neighbors sharing cars for example. In the US many families or friends not even share cars. When I go out with people it ends up with seven people going in 4 cars or similar.

A self driving car takes the pain out of driving so unless society changes a lot we will see more cars driving around (often empty) and people will have longer commutes while sleeping their car.

Sharing a vehicle is not fun when the other driver could: 1. wreck it, 2. not return it promptly, 3. trash it. A self-driving car solves problem 1, partially solves 2, and does nothing for 3.

I guess a self driving shared car needs also to be self cleaning. that may work.

Put together a amalgam self-driving Sanisette [1] and you implement an even more ridiculous aspect of Idiocracy than its La-Z-Boy with a built-in toilet [2]. And while I make a joke about it now, someones in the future are going to convince a line of VCs to incrementally enable people eventually gaming/Facebooking in VR while hurtling down the freeway doing Number Two, and get handsome exits on each step towards that, and it will all be counted as a net economic benefit in the end. I'm either kidding, or will have checked out well before that ever becomes mainstream.

[1] https://en.wikipedia.org/wiki/Sanisette

[2] http://www.eatmedaily.com/wordpress/wp-content/uploads/2009/...

However, there is a flaw in that system, in that most people tend to be on the road at the same time (rush hours).