Friday, February 25, 2011

Is ZipCar really environmentally friendly?

[Originally posted on]

I love ZipCar. I save a ton of money not having to buy a car for my occasional driving use. There is no question that ZipCar is great service - well thought out, great user experience, attention to details, all the requisites for a great company.

As I was browsing around their site the other day, their environmental impact page claiming that ZipCar has green benefits caught my eye. Here's what they are claiming:

Screenshot of ZipCar's Environmental Impact Page

This got me thinking, is ZipCar claiming that using their service is better for their environment per given mile you drive? Or are they trying to say that members will end up driving less and that's where the benefits come in? If its the latter, then ZipCar doesn't really have a green impact - it is just providing a less useful mode of transportation. It would be like saying if we traded in all our cars for horses and buggies we would be more green. Sure there would be less CO2 emissions, but at the cost of not having a workable mobility solution for society. Let's dig in a bit and see which of the two it is.

The first claim is that each ZipCar takes 15-20 personally owned vehicles off the road. Privately owned vehicles in the US tend to only have about a 5-10% utilization rate (and probably lower for ZipCar's demographic), so clearly sharing a single car among members could reduce the number of cars. However, this doesn't mean that there is less "driving" going on. Members are likely to drive the same amount as before, but in a shared vehicle. So in terms of the amount of emissions released, this seems to be unchanged by ZipCar. Its either x pounds of CO2 released by 15 cars or 15x pounds of CO2 released by one car. There are benefits of course to sharing a vehicle - less parking is needed in cities, making finding a parking spot easier for other cars (ZipCars have their own dedicated spot). Less hunting for parking reduces emissions (by more than you think - some estimates peg 20% of the driving time is spent looking for parking). However, unless ZipCar has a massive footprint, the savings here seem negligible.

Next, ZipCar claims that people who use their service funnel their car savings into buying local and sustainable products. Is this real? Sound like a guess to me given there are no citations whatsoever. I highly suspect that they saw there was some correlation between ZipCar users and environmentally responsible citizens, but instead claimed that this was a causality and not just a correlation. There is no reason to believe that becoming a ZipCar user will suddenly cause you to start consuming in an environmentally responsible way.

ZipCar's final two arguments revolve around the assertion that ZipCar drivers drive less miles than private car owners. Well, how could this be? My view is that a customer has a certain mobility/transportation need. The customer then chooses between the various transportation options that both satifies their mobility need and has the lowest perceived cost. A user that switches from driving their own private car to driving a ZipCar still has the same mobility need and thus likely to drive the same set of miles. In another case, people switching from public transit to ZipCar can still satisfy their mobility need, but are using a mode of transportation that is less environmentally friendly. This is not the fault of the consumer, ZipCar is a convenient and economic solution - but in this case not necessarily environmentally friendly. In the final case, you have users who did not have a previous mobility need but because of ZipCar's convenience and economics actually increase their potential mobility - increasing the number of miles driven. I have yet to see a case where ZipCar's economics and convenience had led people to drive LESS - comment if you have some examples.

Now of course I could be wrong. Maybe ZipCar is environmentally friendly. The most compelling argument is that the existence of ZipCar will shift users from using private ownership vehicles to public transit because they know they can use ZipCar as a backup. That is, some people may have turned away from public transit before because they know they need vehicle usage in some cases. ZipCar allows users to shift to taking majority public transit trips and ZipCar for those rare cases where they need a car - this overall causes less miles to be driven. This begs the question of how many people actually shift from private car ownership to mass public transit, a small number I suspect.

Another possibility is that the fleet of ZipCars, on average, is more eco-friendly than the average American car. That is, if ZipCar uses a disproportionate amount of hybrids and fuel efficient vehicles then less CO2 is being released for the same number of miles being driven. I will have to check the stats on ZipCars fleet to confirm this.

Finally, ZipCar has a partnership with ZimRide which encourages the use of car sharing. In this case, ZipCar is advertising another service that actually is environmentally friendly so there is some benefit there. The question again arises of what percentage of trips are incrementally shared because of the ZimRide partnership. This is something GobiCab is trying to address but in a more direct way - cab sharing at airports where single passenger rides are high, and the opportunity to share a ride because of similar destinations is also high.

I've painted a pretty dark picture of ZipCar but this is not my intention. I think it is a great service, less wasteful, more economic and a general benefit to society - however, I believe some of the claims on ZipCars site with respect to their environmental impact are a bit of a stretch. What do you think?


  1. Aleem, I think you're missing the point of reducing the number of cars on the road. Sure, you may not save on emissions, but less people buying cars means less cars being produced. The production of a big hunk of steel with wheels has an impact on the environment both in the resources used in its construction and the emissions/fuel used by the machines doing the construction itself. Also, less cars on the road means less cars being scrapped and trashed at the end of their lifespan.

  2. @Gibnai - that's a good point on production impact of a vehicle but according to

    "Over the life of an average motor vehicle, however,
    much of the environmental damage occurs during driving and is greatly
    associated with fuel consumption. Over the dozen or so years of a
    vehicle's life, nearly 90 percent of lifecycle ("cradle to grave")
    greenhouse gas production for a typical automobile is due to fuel

    So while you are right that producing less cars is good for the environment, it isn't really a large part of the issue.

  3. 10% of the emission of a car's lifespan times say 120,000 less cars is still a decent impact for a single company though, wouldn't you say?

    Not that I care. I have never owned or driven a car and never will. Just sayin I think you're ignoring some of the facts.


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