Self-driving cars are here, and they’re likely here to stay. Google’s fleet has logged thousands of miles already, and other manufacturers are scrambling to get in on the action. While the day when all of our cars are replaced by autonomous robotic models may be far off (if it ever comes), the idea of taxi companies or carriers like Uber switching over to self-driving cars isn’t too far-fetched. When that happens, we’ll be better off: A new Berkeley Lab study finds lower greenhouse gas emissions on a per-mile basis for driverless cars deployed as taxis.

“When we first started looking at autonomous vehicles, we found that, of all the variables we could consider, the use of autonomous vehicles as part of a shared transit system seemed to be the biggest lever that pointed to lower energy use per mile,” Berkeley Lab scientists Jeffery Greenblatt.

Overall, the study found that a self-driving electric car deployed as a taxi in 2030 would have per-mile greenhouse gas emissions anywhere from 63-82% lower than a privately-driven hybrid. Versus a 2014 all-gasoline model, the emissions savings are as much a 90%.

Much of the savings are projected to result from right-sizing, the practice of selecting the size of the taxi based on the passenger’s needs. Today, people in need of a lift can choose from a spectrum of cars with a service like Uber, for instance, but even the smallest UberX vehicle typically seats four passengers and has space for luggage. However, as Google and other manufacturers experiment with different configurations, one- and two- seat cars could be a more efficient reality.

“Most trips in the U.S. are taken singly, meaning one- or two-seat cars would satisfy most trips,” Greenblatt said. “That gives us a factor of two savings, since smaller vehicles means reduced energy use and greenhouse gas emissions.”

Of course, autonomous technology is currently prohibitively expensive, and will likely continue to be in 2030. However, when vehicles rack up taxi-like mileages (40,000-70,000 miles per year), the vehicles actually become cheaper: Fuel and maintenance costs go down, and not having to pay a driver saves funds as well.