The appeal of electric cars is straightforward: Owners get to save money by skipping trips to the gas station and feel good about doing their part to cut carbon emissions. That’s part of the reason why U.S. sales are currently soaring, with electric vehicles expected to make up 10 percent of the cars and light-duty trucks on roads in 2030. This is good news for the climate, since transportation is the single largest source of emissions in the country.

The decision to switch to an electric-powered vehicle benefits 9 out of 10 U.S. drivers, but the lowest income Americans get left behind, according to the results of a new study from the University of Michigan.

A group of researchers at the school’s Center for Sustainable Systems analyzed data on income level, gas and electricity costs, and vehicle-specific greenhouse gas emissions for every census tract in the United States. They found that over 90 percent of vehicle-owning households would see reductions in both carbon emissions and the amount they spend on powering their car by switching to an electric vehicle. These benefits are especially pronounced on the West Coast, where some households could cut their annual transportation bills by $600 or more, and slash their annual carbon emissions by more than 4.1 metric tons, the study found.

The pattern does not hold true, however, for those with the lowest incomes, more than half of whom would continue to be burdened by high transportation costs — defined as more than 4 percent of their income — after trading in their gas-guzzler for an electric car. The study found that households that would receive little benefit are concentrated in Midwestern states with coal and natural gas-reliant energy grids, as well as in Alaska and Hawaii, the two states with the highest cost of electricity.

Read the full article about inequality in electric car benefits by Lylla Younes at Grist.