[matthewdgreen]

Leasing and car rentals have the same problem, which is that you're a single driver hogging an expensive capital asset that you'll use maybe 5-10% of the time. This low capacity factor makes car ownership very expensive. The presumed advantage of self-driving cars is that self-driving vehicles can operate at a higher capacity, factor without incurring the extra costs of needing a human driver to operate them (like taxis) which will make them more useful.

NB: I did not used to think about this much until I recently went to price an extended warranty for my low-mileage car: all of the plans were denominated in years _or_ miles, which meant manufacturers price maintenance in terms of years owned, regardless of usage. The same is true with insurance, which is a huge cost for most drivers: some insurance plans offer a modest discount for extremely low mileage drivers, but to a first approximation the fixed costs of simply owning a parked car are huge. Basically the only saving for owning a parked car is fuel (which can often by offset by the cost of parking, whether that's born by the owner or subsidized by the city.)