Switch to Self-Driving Cars Could Cut Ownership 43%

If all U.S. households switched from conventional cars to vehicles that drive themselves, they could theoretically get by with one rather than two vehicles, according to an analysis by the University of Michigan Transportation Research Institute.

Researchers Brandon Schoettle and MIchael Sivak calculate that in the "most extreme hypothetical scenario," the average household's vehicle ownership would drop from 2.1 to 1.2 vehicles. At the same time, usage per vehicle would jump 75% to about 20,400 miles per year.

But the researchers emphasize a more accurate estimate is impossible because a host of major unknowns. Among them: how self-driving cars are implemented, how well consumers accept them and how effectively households share their self-driving vehicle.

Schoettle and Sivak considered federal travel data to evaluate such factors as when and how household members make trips, how often trips might overlap and the acceptable time gap between trips. Their analysis assumes that a self-driving car would be able to take occupants on errands or deliver passengers to their destinations, then return home unoccupied and pick them up later.