I don't consider Uber a "sharing service." Uber's model will probably be the model for the future, I don't see any reason why it shouldn't be, with the difference that they may maintain the fleet themselves. What is the upside to owning a car if you can dispatch one to your house to take you anywhere in a few minutes, or if you can have micro-rentals of a few days at a time where the car will not return back into the network if you really want "instant gratification" of hopping in the car the instant you want to go somewhere. Look at what Uber is done in cities if you want evidence that this model can have a massive effect on the incentives of car ownership.
Add to this that the public will probably be incentivized to tax or otherwise limit car owners, and the value proposition gets even worse. It could turn out waiting for an automated vehicle from a network to arrive is still faster door-to-door, since it may have privileged access to high-speed roads or lanes that owned vehicles may not, due to regulation a la HOV, etc.
edit: Also I don't disagree that in the early adopter phase autonomous cars may introduce inefficiencies. But the autonomous car is a 100, or even 1000 year invention, not a 10 year one. In many ways it may just be a single one-time event, when ground-based personal transportation for a civilization becomes automated, so it may have no shelf life at all.
> To attack your specific example, why do you assume the cars will drive around passenger-less, and not merely continually make productive uses of themselves, such as by delivering other packages or acting as deliverymen for physical goods?
Because they won't most of the time? Let's say that during peak rush hour, N people + M packages need to be transported. That means that in order to satisfy peak demand efficiently, we need N+M cars and road capacity. During off-peak hours, lets say that only 20% of the population needs to travel. That means you've got the other 80% of the cars sitting around doing nothing just like they are today. If the average distance to nearby parking is say 2 miles, then we have 80% of the cars just driving empty 2 extra miles to prevent themselves from taking up road capacity (while today we trade off by creating parking lots).
Despite that, I do think there will be some improvement in terms of car use. Namely:
* the average car size will shrink to probably that of a smart car (2 seats, little cargo room)
* parking lots will shrink (but not disappear) due to effective stacked parking
* vehicle efficiency will increase (human drivers are inherently bad at maintaining fuel/energy efficiency with acceleration/deceleration)
The danger is that this once again will make car use "cheap" and like the article suggests, extends sprawl yet again. So we'll just have another half a century of poor land use just it might be slightly more efficient this time around.
Regarding you point on peak demand, I would expect that any 'autonomous taxi service' would use demand based pricing to mitigate the impact of peak hours. Essentially this means, that for a lot of people, the cheapest way to get to and from work will still be public transportation/biking/walking (at least during peak hours). Of course, if autonomous vehicles become cheap/ubiquitous enough, at some point along the price curve, it would make sense to have a ton of extra capacity to satisfy peak demand. Also, car sharing services would add another factor into the equation. Taxi companies would need to be profitable, whereas car sharing companies would only need to return enough value to the individual car owners to convince them to participate (i.e. participating in the service does not necessarily have to be 'profitable' for the owner, it just needs to offset enough of their costs to convince them it is worth it).
On your point about sprawl, I can just as easily envision the opposite happening. As car ownership becomes less of a necessity, I do not need to worry about a garage or parking when considering where to live. Additionally, I don't think that autonomous vehicles will necessarily make car use cheap, I think more realistically, the marginal cost of driving (i.e. cost per mile) will still be a non-insignificant amount, but the convenience will increase dramatically (especially for people who do not own cars), but I imagine commuting an hour to work each way using an autonomous taxi service will still cost you a pretty penny (partly due to the demand issues mentioned above). Also, long commutes still suck, even if you aren't driving the car. I participated in carpool for a year (one hour each way, my car was too crappy, so I never drove, just pitched in for gas), and I was able to get some work or reading done, but I still hated it.
Add to this that the public will probably be incentivized to tax or otherwise limit car owners, and the value proposition gets even worse. It could turn out waiting for an automated vehicle from a network to arrive is still faster door-to-door, since it may have privileged access to high-speed roads or lanes that owned vehicles may not, due to regulation a la HOV, etc.
edit: Also I don't disagree that in the early adopter phase autonomous cars may introduce inefficiencies. But the autonomous car is a 100, or even 1000 year invention, not a 10 year one. In many ways it may just be a single one-time event, when ground-based personal transportation for a civilization becomes automated, so it may have no shelf life at all.