You only need the three cars if you insist on owning the vehicle you're riding it. So if Mom, Dad and Kid all need to be somewhere different at the same time, Uber Pool could work for two of the three, or all three while the car is earning more as Uber Black (or the future equivalent). They only need their own vehicle if they want to ride together.

If Mom, Dad, and Kid need to be in different places at the same time during peak travel time, there is still a demand for 3 vehicles regardless of who owns them. The effect on total vehicle fleet is unchanged.

The better pooling effects of subscription or on-demand fleets mitigate this problem in most scenarios, but it doesn't mitigate it during peak times. Peak vehicle utilization will be what drives total vehicle fleet size.

Even if the members of the family are going different places, each of them can likely share a car with other people heading in the same direction (e.g. to the same school or workplace, to the same city from the suburbs, etc.)

The same capability currently exists independently of driverless cars. What makes you think the utilization of this tactic will change with driverless cars?

Coordinating this is a hassle. With driverless cars, you could say "I need a vehicle to take me from A to B" and a vehicle just shows up, possibly with one or more passengers who were already enroute to B. It wouldn't surprise me if that becomes the norm with an option for "I require a private trip" for an extra fee.

I currently have two apps on my phone that provide me a way of saying "I need a vehicle to take me from A to B". Both have attempted to do what you are talking about, but have settled on something more similar to "Walk to checkpoint A and wait for 5 minutes and you'll be dropped off at checkpoint B that is kinda close to where you actually want to go".

As it turns out, coordinating rides is pretty difficult, even with sophisticated software doing a lot of the work for you. Maybe if either of those companies had huge market shares, then maybe the problem gets easier. I'm not counting on it.

Uber and Lyft already do this in San Francisco, and it works very well.

Not sure where you live but I agree with shoyer that Lyft Line and Uber Pool serve this functionality very well in San Francisco, New York, and presumably also the other major metros where they've launched it (Austin, Boston, Chicago, Los Angeles, and Washington, D.C for Lyft Line)

Taxis are expensive and public transport isn't as convenient. A minibus taking me from within a block of my house to within a block of my work would get my business.

Labour costs are a significant part of any such operation, where I live at least.

How about Mom, Dad, and Junior share rides with other Moms, Dads, and Juniors who are headed in the same direction?

Because that is already a possibility (carpooling is an established idea), and the critical reasons why it isn't more popular don't significantly change with automated cars. People don't want to spend their commute with random people who just happen to be going the same direction. Perhaps more important is that it creates a strict commitment to be prepared to leave on time and a reliance on others leaving on time.

> People don't want to spend their commute with random people who just happen to be going the same direction

Many, many people already do this on public transport. What we're talking about is general door-to-door public transport.

Car-pooling is awkward to arrange, particularly for short joined parts of the journey (e.g. picking someone up part way and dropping them off a little later), and it's extremely hard to arrange anything that overlaps such that the first passenger needs to get out before the last passenger (currently would involve handing over the keys to your car).

>Many, many people already do this on public transport

Total fantasy. Virtually nobody uses public transport. 5% of commuters use public transport. Relative to the car-pooling, who sees double the volume of users as public transport, 10%.

http://traveltrends.transportation.org/Documents/CA10-4.pdf

So what? The reason so few people use public transit across the US is very likely because it sucks at getting them door-to-door in a reasonable amount of time.

The question is: if that changes, what might people choose to do? The example of large cities like NYC at least teaches us that the American preference for solo car travel is not fixed.

Guess that depends on where you live. In cities like NYC, or Chicago (where I live), having a car in the city is common, but the minority.

In the US, only NYC has over half of households without a vehicle [0]. Chicago has only 28% with no vehicle.

[0] http://ns.umich.edu/new/releases/21923-hitchin-a-ride-fewer-...

How many people use public transit in Europe, or Japan and Korea?

For commuting, roughly 20% in the UK or about 4 million people (26M working residents, ~80% commuters). About 50% within London.

http://www.ons.gov.uk/ons/rel/census/2011-census-analysis/di...

Close to 20% across the UK (representing about 4 million people) and close to 50% in London (compared to 35% driving).

http://www.ons.gov.uk/ons/rel/census/2011-census-analysis/di...

These are not insignificant figures.

If you say "people don't want to do X" when millions of people in my country already do a more extreme form of X, then I think you're wrong.

I think many people just don't want to coordinate with strangers, like a pickup time, place, etc.

This will be much smoother if you just open an app like Uber and it tells you the next pickup time for where you want to head.

Carpooling in private cars is very different from carpooling in self-driven cars. While you own the private cars, it's very reasonable to expect you not to share the ride with strangers or to occupy another's car. However, if it's a self-driven car which no one owns - it's just like public transit, but way more efficient. Instead of buying a monthly train or bus pass you just pay your self-driven car rental/lease, to be picked up door-to-door at your whim. This will happen and will bring about the 10x change.

As long as cars aren't prohibitively expensive and remain symbols of personal freedom and identity, then people will pay for the luxury of not riding in public transportation.

Some people have an aversion to riding on public transit when it is used by people large income/wealth disparities, i.e. the professional doesn't want to be on the same bus as the indigent person.

Those people might use a vehicle subscription, because the cost of private rides would still be lower than the costs of private vehicle ownership (depreciation, maintenance, insurance). Many people would pay for the privilege of a private ride (like they do with Uber/Lyft now).

If car subscriptions services succeed and are nearly ubiquitous, the personal-freedom symbolism of car ownership will degrade.

Then, if people want to own a car as a status symbol, they will probably be better served by a more expensive one anyway, the same way people buy other status symbols (rose-gold iPhones, etc). Ironically, most of those status-symbol cars will still have an autonomous mode.

I'm not talking about cars as status symbols, but as factors of identity. Teenagers want cars because it is a rite of passage. Half my coworkers want trucks because they are 'outdoors' people. And some do use it as a monetary status symbol. Some people are just car people who have strong opinions about the car they drive because it is part of their self-expression. This is a pretty big thing in American culture.

People pay to use trains when the journey time compared to a car is marginal, since they can do something productive on the train.

Some people pay more to use a first-class compartment.

This is true with current car economics, but in a shared car economy, it will become increasingly expensive to have exclusive ownership, and people will vote with their wallets.

Shared-car design could also be drastically different. I don't want to share a Honda Accord with random people, but I wouldn't mind sharing a road-train that had private compartments for each set of passengers...

You just literally described trains and buses. Don't assume the form of the vehicle remains the intimate 3-across sedan style.

Self-driving mini-vans could lie in the car / public bus & subway trade-off on high traffic commute roads.

car: high flexibility, high cost

public transport: low flexibility (last mile, connections, fixed time schedule), lower cost

self-driving vans: medium flexibility, possibly low cost.

Yeah, but they usually don't originate from the same location. So instead of matching destination, now you have to match destination and departure location.

Yep this is how Lyft Line already works

> would only estimate a 3-5x reduction in fleet size

10x is admittedly bullish. I expect 4 to 7x within 20 years, i.e. 3 to 4 product cycles. But 10x is more reasonable than it seems at face value.

Let's use Manhattan to illustrate. Another HN user (wadenick) kindly provided [1] some references I'd like to point to. Car ownership across the United States stands at 81% of households [2]. In Manhattan it's 23% [3]. Manhattan has roughly fewer than 1/3 the number of cars as the rest of America. This is partly why there are only 39 gas stations in Manhattan (down from 60 in 2004) [4]. Repair shops, too, are fewer and further in between. Many are owned by taxi operators for their fleets' use only.

Uber pays 75% of its earnings to its drivers. How much cheaper could a driverless be? 50% less? How would that tilt our 23% figure? All it takes is half of Manhattan's car-owning households to switch for Manhattan to hit a 7-fold reduction in car ownership from present-day America.

Everywhere isn't Manhattan. Density matters. Less-dense locales will need to accept some combination of higher wait times, higher prices or lower rates of fleet reduction. That said, the scaling economics are nearly identical. Fleets will be cheaper than individually-owned self-driving cars because they can more efficiently use their down time. This, in turn, makes individually car ownership more expensive (by degrading retail-servicing infrastructure and supply chains). That, in turn, makes fleet usage more desirable and so on.

The degree to which this happens may vary. But at its lower bound, I'd posit 4x and at its higher bound over 10. Given that income and urban dwelling are correlated, and continue to increase in their correlation, that bodes badly for the edge-case rural families demanding high degrees of simultaneity at a price even remotely approaching what it costs to maintain a small garage of cars today.

[1] https://news.ycombinator.com/item?id=10837732

[2] http://web.archive.org/web/20140209114811/http://data.worldb...

[3] http://www.nycedc.com/blog-entry/new-yorkers-and-cars

[4] http://www.wnyc.org/story/say-goodbye-manhattans-gas-station...

"Uber pays 75% of its earnings to its drivers. How much cheaper could a driverless be? 50% less?"

Remember that from that 75% is supposed to be things like insurance policies and such, and I suspect that currently drivers aren't bothering to properly insure their cars (using it for a business rather than personal use). In a driverless car case, someone is going to have to pay for that insurance, whether the manufacturer, operator or rider, that cost is going to come from someplace, and will probably be significant. I'm not sure that you could achieve 50% savings, and maybe not even 25%.

"All it takes is half of Manhattan's car-owning households to switch for Manhattan to hit a 7-fold reduction in car ownership from present-day America." But what does that prove? Manhattan isn't a great barometer of anything. Even if they did drop to 14% or so, that's not really moving the needle much either way, is it?

> In a driverless car case, someone is going to have to pay for that insurance, whether the manufacturer, operator or rider, that cost is going to come from someplace, and will probably be significant. I'm not sure that you could achieve 50% savings, and maybe not even 25%.

The fleet provider (e.g. Uber) would surely self-insure. Insurance for self driving cars will be extraordinarily cheap (at least an order of magnitude less than driver based insurance).