Just pointed out a math flaw in parent post. It's obvious where both numbers were pulled from...

Many people would pay a premium not to have to pony up a down payment or deal with oil changes.

What percentage of population? 5%? In mean time, people buy used cars for the amount of down payment, if not less. And do oil changes themselves because it's cheaper.

There're already services that cater to those people. Full-service car leases, regular car sharing etc. People who want that already use them. But they don't seem to get that wide adoption. If shared autonomous cars would be adopted as widely, they wouldn't change traffic flow much.