The Longer You Car Share, The Less You Car Share


This article looks at car sharing, attempting to figure out how many cars are removed from our streets, and what the impact on VMT is.

The consensus is 9-13 cars per sharing vehicle (compared to claims of up to 32 cars).

But the really interesting finding is that there is substantial VMT reduction even though many car-sharing customers are from car-free households. The conclusion is that over time you learn how to use the car less and less, as you get better and better at using other modes.

But the studies by Shaheen and other researchers show that VMT among carsharing customers drops in subsequent years, often quite dramatically, as people figure out that it’s not really so hard to get around by public transit, bike, or on foot. “When people use carsharing, they use it less and less and less,” Shaheen told us.

That matches my personal, anecdotal experience. I think a big part of that is because when each car-share trip becomes an incremental expense, the pricing signals encourage you to think harder about the alternatives.


14 responses to “The Longer You Car Share, The Less You Car Share”

  1. I expect that some other folks end up using it more and then just buying a car. very few would be at an equilibrium

  2. The opposite effect must be in play when you own a car. As you have the fixed expense of the car, you feel more compelled to use it and not look for alternatives. I know that is true in my household even though I bicycle regularly. I just can’t get both of us to use transit or walk when we have the car in the garage.

    Only when the cost to drive more costs a lot more (congestion charges, higher fuel taxes, VMT charges) will people move to looking at other options.

    • And here’s an anecdote for your anecdote…

      I own a car and don’t feel compelled to use the car all that often, fixed costs and all. In fact, the car is always the last option, only used when I don’t think walking, biking, or transit will take me where I need to go efficiently, if I’m going on a trip, or if I need to haul something large. But it’s sure nice to have a car on-demand at all times when those occasions arise.

      Variable costs such as gas, parking, tolls, pay-as-you-drive insurance, etc. can help encourage people to drive less, even if they feel compelled to own a car.

  3. That was exactly my experience with not owning a car and using car share as well. I used it quite a bit at first, but for the last couple years now I have pretty much not used car share at all.

    This also backs up the theory that self driving cars may very well lead to much better public transit. That one goes: self driving cars will lead to increased car share since they essentially become readily available inexpensive taxis and owning a personal one will make less sense since you’d have to deal with and pay for parking. As people consider those costs then the ideas of freeways and major materials becomes pretty silly, if everyone is headed in the same direction they might as well be in the same vehicle since it would be much more efficient and less expensive. At that point people only use car share for first mile and last mile parts of a trip, then looking at those costs walking or biking for first mile and last mile starts to make more sense and they use car share, and therefore cars in general, less and less particularly in urban areas.

    • Daniel,

      Your point is sound, but it overlooks one important point: in car share the shared vehicle “belongs” to the renter for a period of time. There’s no possibility of a drunk or otherwise obnoxious person interfering with the renter’s peace.

      That’s worthwhile to a lot of people; Americans have shown a strong propensity to pay a non-trivial part of their income to obtain it. Urban folks are more used to the jostling, but I don’t think you’ll find that suburbanites will go for it.

      • It does lead to interesting questions though.

        What will be the place of a transit agency if self-driving buses that are trusted by the public become common? Since the highest cost of operating a bus is the driver would that lead to different tiers of service? Maybe TriMet would end up just operating some self-driving trains as trunk routes for those who can’t afford to take a private self-driving bus or car home?

        Maybe some buses will cost the equivalent of $6 each way today, but will have security on them and lots of amenities, and only 10 passengers all from the same neighborhood so they get the fastest and most direct trip door to door. No parking fees, just $16 round trip.

        At the same time for a 2014 $1 ride you could get on a bus with security cameras and no frills. It would carry a crush load of passengers while meandering all over, but eventually you’d get close enough to walk home.

        Maybe other companies would step in with a variety of offerings in between with different price points. Some could run buses/vans from MAX stops through neighborhoods. How often the service would run would be a variable, comfort level another, as well as things like cost and time to get to your destination.

        Or you can hire a private self-driving car for $12 each way. If you carpool with people of your choosing it’s fairly cost effective, and you choose the waypoints, but you pay a premium for it.

        Obviously all of these prices are just examples, but it seems like a market that various companies could have incentive to get into. And it eliminates a lot of the costs of transit (while creating all kinds of discussions about automation and the resulting loss of jobs.)

        It sounds like it’s far in the future, but by the time some of us are of retirement age it might be reality.

  4. What happens when car sharing firms mimic cell phone providers and offer a set number of miles/minutes per month at a price less than the base unit charge? What would happen if “unlimited” usage plans were offered?

    • Dude,

      Cell phones are quantum thingies. The next call costs very nearly nothing for the provider to connect.

      Cars are Newtonian thingies. They require gasoline, oil, rubber and lots of other inputs to operate. The next mile costs the provider a non-trivial amount; the IRS says fifty-six cents.

      Your analogy is not valid.

      • Are you saying that it’s impossible for car sharing firms to offer bulk discounts?

        Even relatively small discounts could make a difference.

        • I was mostly responding to your proposal for an “unlimited” option. Ain’t gonna’ happen, for the reasons stated.

          Bulk pricing contracts? Why? The only people who would take them are folks who make the same trip on a regular schedule; otherwise why pay for a fairly expensive something you might not use? So most are going to be work-related. If such a trip is during the peak period, the firms are just giving away revenue; the cars would be in use anyway.

          You might find some niche opportunities for bulk pricing in off-peak usage times, but that’s about all.

          • Folks, Zipcar already offers discounted membership plans – EVP Extra Value Plans – as an incentive for heavier users. And some carshares offer variations in pricing to encourage weekday usage, Especially attractive to business usage.

            • Thank you, Dave. You sound like you know about the business, so I’ll admit I was wrong. I’m amazed that they need to give preferential pricing for Weekdays, though.

              That sounds very much like they do not have a viable long-term business,or at least they’re running too many cars.

              Any business whose major capital asset is used only two-sevenths of the time is in trouble unless that asset returns a BIG return.

          • If Car2Go offered a bulk package of minutes per month I’d sign up in a second. I basically spend with them per month what I used to spend just on car insurance. If they could make it more cost effective for me to commit to using their cars for 100 minutes a month for say, $35 instead of what would usually cost me $41 I’d be all over that.

            Maybe not unlimited, but a bulk discount would get me to use them a bit more. I don’t think Daimler AG started Car2Go out of the goodness of their hearts. I’m sure they’ll consider all kinds of ways to get their cars used.

            As you mentioned, I could see time of day eventually becoming a factor, but that can also scare off users who are willing to wait for a service.

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