Driving around U.S. cities, it may not seem like there are fewer cars on the road. Many places are as congested as ever. But a new study suggests that it could be a lot worse. Changing attitudes about owning a vehicle and the rise of sharing services like Zipcar have indeed reduced the number of cars on the road from what otherwise would’ve occurred.

AlixPartners, a consultancy that has automotive clients, interviewed 1,000 licensed drivers in 10 U.S. metro markets to understand what’s motivating people to use car-sharing services and what effect that’s having on vehicle sales. It estimates there are already 500,000 fewer vehicles on the road because of sharing’s popularity, and that lost sales will only increase. By 2020, it expects 4 million people will be sharing cars, and that there will be 1.2 million fewer cars.





The survey covered Austin, Texas, Boston, Chicago, Miami, New York, Portland (Oregon), San Diego, San Francisco-Oakland, Seattle, and Washington, D.C. Awareness of car-sharing was strongest in Boston, where Zipcar was founded and first launched. Avoidance of ownership was highest in New York and Washington. Younger consumers and, surprisingly, households with children were most likely to do without their own car.

Among people who have already shared a car, 51% said they’ve avoided purchasing or leasing, and that 45% expect to continue to so in the future. AlixPartners multiples the average of those two figures, 48%, by the number of people who on average use each shared vehicle. That leads to the estimate that a single sharing vehicle equates to 32 personal vehicles that don’t get purchased.





To provide a comparison with major cities, the consultants also interviewed 1,000 people nationally. And, though the number of car-sharers and avoiders was lower, it was still significant. A third of respondents (34%) have foregone purchasing or leasing a vehicle, while 21% expect to act similarly going forward.

Getting cars off the road should have environmental benefits, particularly in reducing local pollution. But the survey found that wasn’t a top concern for sharers. Cost and convenience rated highest as reasons for sharing over owning (56% of people chose either of those). Only 23% cited the environment as a primary factor.

AlixPartners expects car-sharing to keep up its growth because owning isn’t getting cheaper or more convenient. It points, in particular, to single way services, which make one-way rides possible, and more smartphone adoption, which makes reservation, locking, and locating a vehicle easier. Driverless cars could also give the industry a bump once they start appearing, the report says.