The Case for Self Driving Cars as a Climate Solution

A lot has been written recently about how autonomous vehicles would be a climate disaster.

The most compelling narrative comes from David Zipper, who argues that the advent of cheap Robotaxis will induce so much demand that they will dramatically increase vehicle miles traveled and road congestion, all while reinforcing America’s love affair with cars and car-centric cities. While induced demand is a real phenomenon, I do not fear that our cities will be overrun by carbon-hungry robot cars. Rather, autonomous vehicles can be an important part of our climate response, contributing to the livability of our cities and the sustainability of our transportation systems.

To understand why, consider Zipcar, America’s first modern carshare at scale. Zipcar was founded to usher in a more sustainable system for automotive transportation. Since 2000, Zipcar has delivered just that to its customers. According to Zipcar’s 2021 Impact Report, Zipcar generated the following results:

In Seattle, the average number of vehicles per household for Zipcar members fell 34% between 2019–2021, compared to a 13% increase in Seattle for non-Zipcar members during the same period

Zipcar members reported driving 40% fewer miles than they did before joining.

Data shows Zipsters rely on walking, biking and public transit for short trips, and turn to car sharing for longer, purpose-driven or recreational trips to out-of-town destinations

Zipcar remains an affordable mobility alternative to car ownership, with members saving an average of $784 per month on average compared to car owners.

Zipcar members owned fewer cars, paid less per month, drove fewer total miles, and successfully shifted many of their trips from cars to transit, walking, and micromobility. While no system is perfect, Zipcar has inspired climate-positive behavior changes that the nation desperately needs but hasn’t otherwise cracked. Zipcar has been a climate success for those it serves.

Unfortunately, carshares like Zipcar remain a niche solution, serving only people and areas that meet ideal market conditions. A viable carshare needs to be both cost competitive and available when and where you need it. Making carshare more convenient for more people, then, requires more vehicles placed in more locations, locations which by definition are prime real estate. If a carshare operator chases greater convenience, they quickly find themselves to be no longer cost competitive.

Autonomy fixes carshare. Imagine that instead of walking 15 minutes to the nearest Zipcar, you could have one autonomously delivered to you curbside. Relative to traditional carshare, autonomy can deliver vehicles to more people on demand, increasing convenience by expanding the reach of each vehicle on the network without consuming more valuable land or adding excessive safety stock. It can approach the convenience of rideshare and the cost structure of car rental. Autonomy can turn carshare into a mass market solution, which in turn can scale the climate benefits of carshare.

While the conclusion that a driverlessly delivered carshare would have a net positive climate impact is hypothetical (as are all predictions about autonomous vehicles at scale), there are many first order reasons to believe that this will be the case.

Autonomous shared vehicles empower users to more precisely match vehicle type to need

If we want to break America’s love affair with comically large vehicles, one of the best things we can do is to make it cheap and convenient to rent the vehicle you need for the use case at hand. Olaf Sakkers defines the Trip Economy in his Mobility Disruption Framework. He summarizes in a tweetstorm:

When considering vehicle GHG emissions, Uber and Lyft are not the problem. Car ownership is the problem. Uber is actually a key part of the solution. Uber has so quickly become a part of our culture — and created so much controversy along the way — that we fail to see that it gave birth to the modern *trip economy*. We call the purchasing of individual trips — transit, ridehailing ride, short term car share, shared scooter or e-bike (micromobility) ride, a food or package delivery (with increasingly more options!) — the trip economy.

The transition to a Trip Economy began with Uber, but it progresses with every efficiency gain across all vehicle and transit categories. The easier it becomes to rent whatever you need when you need it, the easier it becomes to forgo the purchase of a car that can do everything.

How does this help to shrink the average car size in this country? When Americans buy vehicles, they optimize for the worst case. When traveling on demand, they optimize for cost and convenience. This is why the best selling car in the US is the Ford F150, but the most common Uber is the Prius.

If Americans knew they could get the pickup, the AWD SUV, or the long range road tripper reliably and cheaply the few times per month that they would need it, then they could more confidently purchase a sensible commuter car or forgo a car purchase altogether. Wishful thinking? Zipcar members might suggest otherwise.

Further, autonomous shared vehicles can usher in new form factors, like neighborhood electric vehicles (i.e. fancy golf carts) or autocycles (enclosed three wheel motorcycles). It’s a tall order for American consumers to spend $10,000 on a souped up golf cart, but to rent one for a few bucks to scoot around town for an afternoon can be a winning pitch.

Autonomous shared vehicles can speed the adoption of EVs

Our ability to electrify our vehicle stock is rate limited by the amount of precious minerals we can pull from the ground. If we want to maximize the number of trips we can shift from gas-powered autos to EVs in the near term, we have two options:

• Maximize the utilization of each electric vehicle
• Maximize the number of electric vehicles that you build by shrinking their sizes and battery capacities

Cheap, convenient shared fleets are the best way to achieve both. Most private cars sit dormant 95% of the time. We can make the most of each vehicle by sharing it across multiple users.

The fastest way for short range EVs to go mainstream is in a shared fleet. Again, Americans buy for the worst case but rent for the cheapest price. When Americans buy EVs, they demand ranges of 300 miles. When renting for a few hours, a 100-mile range might be just fine, especially if it’s a few dollars cheaper.

Autonomous shared vehicles can make transportation more affordable overall

Autonomous shared vehicles can make automotive transport cheaper for more people by sharing the cost of vehicles across many more consumers. With shared vehicles readily available, consumers save money by buying smaller cars or fewer cars. Consumers also save money by shifting applicable trips to much cheaper forms of transit, like micromobility, public transportation, or walking. Though skeptics fear that a reduction in transportation costs will inspire crippling growth in automobile travel, we can make transportation cheaper while simultaneously decreasing car miles driven, just as Zipcar has done for its members.

All of this is theoretical, of course. Self driving technology requires further investment before it is viable at scale. The feasibility of self-driving technology is a topic for another day. The skeptic’s warning is that even if autonomous driving solutions can be delivered safely and cost effectively, the end state is not a future worth building towards. I believe that the autonomous future is a bright one that is better for people, cities, the planet, and the generations to come.