Open Google Maps for a routine drive and there is a good chance the suggested route is not the fastest one. It is the one that burns less fuel. Since late 2021, Google has been quietly steering drivers toward lower-emission paths through a feature called eco-friendly routing, and as of spring 2026 it remains the default setting for most users in the United States, Canada, Europe, and roughly 40 other markets. The change is easy to miss: a small green leaf icon next to the recommended route, a one-line note about fuel savings, and an arrival time that is usually within a minute or two of the fastest alternative.
How the routing works
The technology behind the shift comes from the National Renewable Energy Laboratory, a U.S. Department of Energy facility in Golden, Colorado. NREL developed a modeling tool called RouteE, which estimates how much energy a vehicle will consume on a given road segment by factoring in elevation changes, stop-and-go traffic patterns, speed limits, and intersection density. Google partnered with NREL to integrate that prediction engine directly into Maps.
According to NREL’s partnership announcement, “Google Maps will default to the route with the lowest carbon footprint when it has approximately the same estimated time of arrival as the fastest route.” That language confirms the behavior is opt-out, not opt-in. Unless a driver has manually toggled the setting off, the algorithm is already choosing efficiency over raw speed on qualifying trips.
The technical backbone is publicly documented. NREL hosts RouteE’s developer documentation on its API portal, and peer-reviewed papers describe the machine-learning models that predict energy consumption across different vehicle types, including gasoline cars, hybrids, and battery-electric vehicles. Google’s own support pages explain that when eco-friendly routing is active, the app weighs fuel efficiency alongside real-time traffic and road conditions, then recommends the most efficient route whenever the time penalty is negligible.
What drivers actually see
In practice, the experience is subtle. A driver commuting from a suburb into a city center might be routed along a slightly longer path that avoids a steep hill climb or a stretch of road with heavy stop-and-go congestion. The app displays the estimated fuel savings as a percentage next to the route, and the green leaf icon signals that the eco-friendly option is active. If the fuel-saving route would add significant time, Maps still defaults to the faster path.
Google’s methodology paper on the feature describes how its AI layer favors routes with fewer elevation changes, less idling, and more constant cruising speeds. For electric vehicles, the system accounts for regenerative braking potential on downhill segments. The result is a routing engine that treats energy consumption as a first-class variable rather than an afterthought.
To check whether the feature is active on your phone, open Google Maps, tap your profile icon, select Settings, then Navigation, and look for Route preferences. If “Prefer fuel-efficient routes” is toggled on, the app is already making these choices on your behalf. Turning it off restores pure fastest-route behavior.
Where Waze fits in
Google acquired Waze in 2013, and the two navigation platforms share underlying mapping data and infrastructure. Waze has introduced its own fuel-efficiency features over the years, including route suggestions that account for traffic flow and stop frequency. However, no official statement from Waze or Google has confirmed that Waze uses the same NREL-powered RouteE model or applies the same default eco-routing logic that Google Maps does.
What is clear is that Waze’s routing algorithms have evolved to factor in efficiency-related variables like congestion avoidance and smoother traffic flow, which overlap with some of the goals of eco-friendly routing. Drivers who use Waze can check their in-app route settings for any fuel-efficiency preferences, but the documentation is less explicit than what Google Maps provides. Until Waze or Google issues a specific statement, the degree to which Waze mirrors the Maps default remains an open question.
The emissions question
Google has published internal estimates suggesting that eco-friendly routing has helped avoid millions of metric tons of carbon dioxide equivalent emissions since the feature launched. In its 2024 Environmental Report, the company cited a figure of more than 2.9 million metric tons of CO2e reduced globally through the feature. Those numbers, however, come from Google’s own models and have not been independently verified by a government agency or academic institution.
NREL’s published research validates RouteE’s predictive accuracy in controlled testing environments, showing the model can estimate vehicle energy consumption with reasonable precision across diverse road conditions. But aggregate, real-world results from the Google Maps deployment have not been published by NREL or any third party. The gap between modeled savings and actual pump-level reductions is something transportation researchers have flagged as an area needing independent study.
Behavioral questions also linger. Neither Google nor NREL has disclosed how many drivers have left eco-friendly routing on versus how many have switched it off. Research on whether algorithmic nudges in navigation apps produce lasting changes in fuel consumption, or whether drivers simply override suggestions over time, remains thin. Without that data, the real-world climate impact of the feature is difficult to quantify with confidence.
Why a default setting carries outsized weight
What makes this story significant is not the technology itself but the decision to make it a default. Decades of behavioral economics research show that default options carry enormous influence over user behavior. Most people never change factory settings on their devices, and navigation apps are no exception. By making eco-friendly routing the out-of-the-box experience, Google effectively enrolled hundreds of millions of drivers into a fuel-saving program without requiring them to make an active choice.
That approach has drawn both praise and scrutiny. Environmental advocates see it as a rare example of a tech company using its platform scale for measurable climate benefit at almost no cost to users. Critics, including some driving enthusiasts and logistics professionals, argue that routing decisions should prioritize the driver’s stated preference for speed unless the driver explicitly opts into efficiency. The tension mirrors broader debates about when companies should use default settings to steer behavior toward outcomes the user did not specifically request.
Navigation apps have become a quiet but powerful layer of transportation infrastructure, shaping how billions of trips unfold every year. By adjusting the algorithm to reward efficiency when the time cost is nearly zero, Google and NREL introduced a nudge that most drivers will never notice. Whether that invisible shift translates into measurable reductions in fuel use and emissions is a question that only independent, large-scale studies can answer. For now, the green leaf icon on your next route suggestion is the clearest sign that the code under the hood has already changed.
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*This article was researched with the help of AI, with human editors creating the final content.
