What would you do if you could magically reclaim all the time you spend behind the wheel of a car? If you could sit back and relax, knowing that your commute is safer than ever before? Ultimately that’s the future that autonomous vehicles1 are promising.Development of automated driving is far enough along for people to start thinking about what drivers would do with all that free time were it available. Some people imagine sending their cars to pick up milk from the store, having the family car drive little Emily to her soccer practice, or getting into pajamas and curling up to sleep during an overnight long-distance drive.It’s hard to know, though, what people will really do once self-driving cars are common. Part of the problem, of course, is that we don’t yet know what the technology will be capable of and how much it will cost. What we do know is that autonomous vehicles are on their way to being a safe alternative to human-operated vehicles. Autonomous cars will not experience frustration or become tired after a long trip, hopefully resulting in safer roads and fewer accidents. In a recent paper, my co-authors and I tried to figure out what might change in a world of self-driving cars by looking at how people use their time. We found groups of people who might save large amounts of time by using self-driving cars and identified what they might do with all that spare time.The lessons of tracking time[5]Governments and researchers around the world study how people use their time by asking people to fill out time diaries: lists of what activities they do, where and with whom, from when they get up in the morning until they go to bed at night. Survey makers work hard to get a representative sample of the population.In the U.S., the Bureau of Labor Statistics gathers around 11,000 daily time diaries each year. A co-author and I have previously used these data to identify wide variations in how much time Americans spend watching television: 14% of the population watches 7.7 hours a day!Because time diaries document what people are doing now, using them to explore potential future changes stemming from radical shifts in technology and lifestyle is difficult. For our research, we identified groups of people who might save the most time if they used autonomous vehicles, and imagined their lives becoming more like those who drive less.Giving commuters a breakFor instance, we looked at commuters who drive for long periods to and from work. Many U.S. workers drive a lot: 19 million drive 2.5 hours a day. In contrast, 78 million other workers drive about one hour a day. The differences in time diaries from members of each group suggest that the people who drive longer do less of other activities to make time to commute.People who drive longer get 30 minutes less sleep, watch TV a half-hour less, and do 30 minutes less work than their counterparts who drive less. If an autonomous vehicle were available, those long-duration drivers would presumably be very interested in catching up on sleep, favorite TV programs, and perhaps even some work.[10]There are also public transit riders who spend a very long time traveling each day. About 1 million people spend a whopping 3.8 hours a day riding buses, trains, subways, and other forms of transit. Another 3.8 million spend 1.8 hours on transit vehicles. Though they can use mobile devices, people who spend more time on transit are, like the drivers, sacrificing sleep, TV watching, and work to get the extra travel time.Helping people who can’t driveAutonomous vehicles can also help people get around if they’re unable to drive — for instance, because they’re too young, too elderly, or otherwise medically or physically restricted from driving.When we looked at elderly people, we compared differences in how retirees older than 75 use their time, compared to younger retirees between ages 60 and 75. The older group travels 14 minutes less each day than their younger counterparts. They also shop 7 minutes less and socialize 8 minutes less each day. That adds up to around 30 minutes a day less time outside of the home, much of which is spent sleeping more.It may be many years before it’s clear how people will change their lives to adapt to the advent2 of autonomous vehicles. And the societal changes in traffic, commerce, and media consumption may take even longer to measure. But our research suggests there are plenty of activities people might want to take up to fill the time they now spend driving or in transit. Personally, once autonomous vehicles are available and safe, I look forward to taking my hands off the wheel to enjoy the view and let my mind wander.