Electric cars keep getting cleaner, despite efforts by the EPA and NHTSA to roll back pollution standards on cars and powerplants.

That's the conclusion of the latest report from the Union of Concerned Scientists which annually measures the environmental impact of driving an electric car.

The study rates the environmental impact relative to gas cars in equivalent miles per gallon.

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The organization updated its widely-used 2009 study with the latest data available from the EPA from 2018.

It shows that counting the power used to generate electricity the average electric car produces the equivalent greenhouse-gas emissions of a gas car that gets 80 mpg.

Although the fuel economy of gas-powered cars has increased significantly at the same time, no gas car currently achieves an 80 mpg fuel economy rating.

2018 U.S. electricity generation sources [SOURCE: U.S. Energy Information Agency]

As before, the UCS data, overlaid on a U.S. map, shows that some regions of the country have cleaner electricity than others, so electric cars driving in those regions are responsible for commensurately fewer carbon-dioxide emissions. New study still shows the cleanest power in the U.S. on the coasts, where most electric cars are sold. The UCS notes that 75 percent of Americans now live in areas where the average electric car is cleaner than a gas car that gets 50 mpg.

The map shows dramatic progress since UCS first did the geographic analysis in 2009, however.

2018 Nissan Leaf with EVgo fast charger at NJ Turnpike Molly Pitcher travel plaza, Feb 2018

Not counting northern Alaska, the cleanest region for electricity production in the U.S. is California, where an average electric car produces no more pollution than a gas car that gets 109 mpg. The dirtiest region is Oahu, in Hawaii.

Pockets of the Midwest still heavily dependent on coal power—particularly eastern Missouri and Wisconsin and southern Illinois—are less advantageous for electric cars. On average, they produce emissions there equivalent to a gas car that gets 39 mpg—better than most gas cars but lagging some of the most efficient hybrids.

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Parts of the upper Midwest—Chicago, Indiana, Ohio, Michigan, and parts of northern West Virginia and western Pennsylvania—as well as some Great Plains and Rocky Mountain states—Kansas, Oklahoma, Colorado, and some adjacent areas—the average electric car would produce emissions on par with a gas car that gets 46 to 50 mpg, similar to some of the best hybrids, but not much better.

The UCS points out that some electric cars, such has the Tesla Model 3, the BMW i3, and the Hyundai Ioniq electric, are significantly more efficient than the average electric car and would generate no more pollution than a 50-mpg gas car even in regions with the dirtiest power.

Another improvement that stands out from 2009, however, is that the cleanest hybrids have also become much more efficient, with the most efficient hybrids averaging 55 to 56 mpg, up from the mid-40s at the time of the earlier study. The areas where an efficient hybrid might be cleaner than an electric car have expanded in some regions.

UCS 2009 EV emissions mpg map

The regions where the average electric car produces more emissions than a 40 mpg or 50 mpg gas car, however, are each significantly smaller than they were in 2009.

The UCS attributes the improvements to decreasing use of coal in electricity production and growing natural gas and renewable power sources. Since 2009, coal has fallen from almost 50 percent of electricity production in the U.S. to less than 30 percent. The cautionary note, especially in discussing coal, is that this UCS data doesn't include smog-forming emissions such as nitrogen oxide, carbon monoxide, and particulate matter—emissions components that would likely go up (in the short term) with higher power demands from the grid.

Natural gas has grown from just over 20 percent to more than 30 percent, while renewables such as solar and wind have grown from single digits to 10 percent of U.S. energy production.

The UCS bases the study on emissions data from the EPA and energy production data from the Energy Information Agency.