Why Uber is fundamentally different from the private car
by Rik Williams, Senior Applied Scientist — Policy Research, and Adam Gromis, Global Lead on Sustainability and Environmental Impact
Last month, researchers at Carnegie Mellon University released a new study about the environmental and traffic impacts of ridehail compared to private vehicles. To do so, they compared 100,000 private car trips with a simulated scenario where they were all replaced by ridehail trips. The study looked specifically at the indirect cost to society (“externalities”) of both the scenarios.
This study is one of the first credible efforts to quantify local air pollution impacts from ridehail trips versus those in private cars, finding 50–60% lower local pollution (e.g. NOx, PM2.5 and VOCs) with ridehail through the avoidance of “cold starts’’ and relatively newer, lower emitting vehicles. Greenhouse gas (GHG) emissions, however, are about 20% higher for ridehail due to “deadheading”, or additional miles driven to pick up passengers. The GHG results corroborate our own numbers and other recent studies that compare ridehail and private cars on a per trip basis (e.g. Union of Concerned Scientists 2020, International Transport Forum 2020, California Air Resources Board, CARB, 2019). Importantly, the study finds ridehail trips produce 3–12% lower externalities for local and GHG emissions combined.
On the other hand, per the study, all vehicle miles — including deadhead miles — have other costs beyond emissions including congestion delays, crashes, and noise. Given the addition of deadhead miles, the authors conclude that the total external costs of the simulated scenario with ridehail trips is higher than one with private cars.
We commend the authors for their careful and comprehensive work on this important topic. The results are nuanced, provide vital policy context, and raise interesting questions for future research. We also agree with their recommendation to pursue comprehensive policy solutions such as road and emissions pricing for all travel modes. Unfortunately, some of the nuance seems to have been lost in the media, with several articles making the startling implication that car ownership is the best choice for the planet and climate. At the root of this misunderstanding is the assumption that ridehail and private car trips are perfectly interchangeable. Below, drawing from our own data as well as external sources, we discuss why this assumption is deeply flawed.
Riders use Uber occasionally to support low-car and lower-emission lifestyles
Ridehail trips on Uber’s platform are not designed to replace 100% of anyone’s trips, in private cars or otherwise. On the contrary, ridehail is designed for supplemental and occasional use, to support and enable low-car and lower-emission lifestyles.
Mobility is such an integral part of our lives that we often take it for granted, but people in the US take a surprisingly large number of trips: about 1.1 billion per day (pre-COVID), or 23 per week for every person in the US — the vast majority of which are by private car. By contrast, in the last complete pre-pandemic quarter (fourth quarter of 2019), over 80% of riders averaged less than 1 trip per week with Uber. We’ve previously seen evidence that trips with Uber are used to fill gaps in daily travel patterns, improve access in areas where public transit service is sparse, and help people bridge the last mile between transit stations and their destinations.
All of this reinforces the idea that ridehail serves as occasional “mobility insurance” when other modes are unavailable or infeasible for some reason, rather than as a primary mode of travel for most people. Indeed, it’s been known for years that Uber riders tend to own fewer cars and use more public transportation than the general population. Living car-free is one of the single most important steps a household can take to reduce their carbon footprint, and reliable access to on-demand transportation when it’s needed helps households achieve this.
Car owners drive their cars. A lot.
In a 2018 blog post, we dug into then-new data from the National Household Travel Survey (NHTS), the definitive source for understanding travel patterns of people living in the US. One finding that jumped out at us, copied below, is the stark disparity between car-owning and non-car-owning urban households. While households without cars use a roughly even mix of public transit, walking/biking, and other people’s cars to get around (along with a sliver of ridehail and taxi use), car-owning households take 85% of their trips by private automobile:
In a sense, this shouldn’t be surprising at all. A car is a major investment with large sunk costs that apply whether or not you actually drive (insurance, lease payments/loan interest, registration, parking, age-based depreciation). In addition, private car infrastructure and fossil fuels are generally well-subsidized by all taxpayers including households that do not own cars (numerous papers support this view, such as this and this). Therefore, people who own cars are highly incentivized to use them. Most parts of the US, even large cities, are designed such that a car is the most viable way to get around. And, unlike public transit, walking, bikeshare, or ridehail, when someone leaves home in a private car they’ve essentially committed to using that car for their return trip. As TransitCenter found in a 2019 study: “the private car is transit’s major competitor.”
Working towards sustainable urban mobility
Even though ridehail and other on-demand (e.g. taxi) trips comprise a small fraction of overall travel (less than half a percent in the US, and 0.1% to 2.5% in European countries), understanding their impact and taking steps to minimize negative externalities is important. That’s why we committed to reaching 100% of rides with Uber to be in zero emission vehicles, micromobility, or public transport by 2030 in the US, Canada and Europe, and by 2040 everywhere we operate globally. Ultimately, however, privately owned vehicles consume about half of all transportation energy globally, and substantial reductions in car ownership and use are needed to achieve a sustainable transportation future. A competitive alternative — including public transit, walking and biking infrastructure, micromobility options, and the occasional ridehail trip — can help make that happen.
While we agree with many of the CMU report’s findings and recommendations, a number of outlets have unfortunately drawn a false equivalence between trips with a private car and trips with Uber. We strongly disagree with the takeaway that car ownership is better for the planet and climate, and will continue to support and enable multimodal, robust, resilient, and lower emission (eventually electrified) urban mobility networks that provide an attractive, more sustainable alternative to personally-owned vehicles.
