Apparently, location, location, location is the latest twist on electric vehicles and the environment: Whether an electric car such as the Nissan Leaf protects the atmosphere from greenhouse gases depends on where it’s charged, according to a new study. Such a car is no better than a standard gasoline-powered subcompact such as a Hyundai Elantra in cities such as Denver and Wichita, but far exceeds even the best hybrids in Southern California.

That’s the findings of a study of electricity generation, greenhouse gas emissions and electric vehicles by the Union of Concerned Scientists. The variations in how beneficial an electric vehicle is for reducing pollution that causes global warming result from regional differences in how electricity is generated.

The scientific organization, which is a vocal proponent for federal requirements mandating increased fuel efficiency in vehicles, said in regions covering 45% of the nation’s population, “electricity is generated with a larger share of cleaner energy resources — such as renewables and natural gas — meaning that EVs produce lower global warming emissions than even the most efficient gasoline hybrids.”

Read more about electric cars (EVs).