Why Car Sharing Won't Reduce Emissions

In analyzing the potential for growth of car-sharing in the United States, a new study (pdf) by the RAND Corporation estimates that as many as 7.5 million Americans (4.5 percent of all eligible drivers) could end up using the service in the future, up from 560,000 today. And while the RAND study authors - Keith Crane, Liisa Ecola, Scott Hassell, and Shanthi Nataraj - point out that such a shift could have significant benefits such as easing congestion, reducing the need for parking, and reducing transportation costs, they also report that the potential of such a shift to reduce energy use and carbon pollution is minimal. 

"Here are the numbers: If 7.5 million Americans signed up for
car-sharing services, the RAND study estimates that greenhouse-gas
emissions from all U.S. vehicles would decline just 0.6 percent. If we
got outlandish and assumed a future in which 20.3 million Americans (or
about 12.5 percent of all eligible drivers) used car-sharing, then
emissions from light vehicles would still just drop 1.7 percent."

According to Plumer, the reason for the meager decline is due to the current driving patterns of those most be likely to use the service. 

"For the most part, the people who sign up for
car-sharing services were barely driving anyway. On average, Americans
who use these sharing services see their car ownership numbers drop from
0.47 cars per household down to 0.24 cars per household. In other
words, they went from barely owning cars to barely owning cars. In
contrast, car ownership for the country as a whole is about 1.87
vehicles per household."

"Indeed, as StreetsblogDC's Tanya Snyder points out, public transportation - taking the bus or train - is a much more effective way for city dwellers to cut emissions."

Thanks to Daniel Lippman