One-way car-sharing services in North America are helping to lower pollution levels and traffic volumes, even when measured across just the past three years, according to a new study.

The study, conducted by the University of California, Berkeley’s Transportation Sustainability Research Center (TSRC), focuses on one car service, Daimler-Benz-owned car2go, and on data collected specifically from its 95,000 members in Calgary, San Diego, Seattle, Vancouver and Washington, D.C.

Each vehicle in the car2go fleet has removed as many as 11 other cars from city streets, quotes the study. Extrapolated across the five cities mentioned above, that means the car-sharing service has cut down the number of cars on the road there by approximately 28,000, reducing congestion and freeing up parking spaces in the process.

“Our exhaustive, three-year research effort into one-way car-sharing reveals that car2go vehicles result in fewer privately-owned vehicles on the road, fewer vehicle miles traveled and a reduction in greenhouse gas emissions,” said Susan Shaheen, co-director of the TSRC.

The car-sharing service’s other positive side effects include the number of members – between two and five percent of them – who’ve sold their personal vehicles. According to the study, the average age of those cars was 14.4 years, so of the vintage among the most polluting and least economical vehicles on the road today.

An additional seven to 10 percent of members say they won’t need cars of their own because they’ve signed up for the service.

Because one-way services like car2go don’t require users to make return trips after their booking is over, they reduce the number of miles traveled per person per year by about 11 percent. In turn, this reduction cuts personal greenhouse gas emissions by about 10 percent.