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The study looks at the energy required to build the car, keep it fueled up, and recycle it.

The Mitsubishi Mirage should replace the Tesla Model S as the poster child of the eco-friendly car segment, according to a new study conducted by the Massachusetts Institute of Technology (MIT).MIT researchers examined the amount of carbon dioxide emitted by the Mirage, the Model S, and the BMW 750i xDrive over the course of their respective life cycles. They factored in the energy required to manufacture the cars, to keep them fueled up with either gasoline or electricity, and to recycle them.

The Mirage emits 192 grams of CO2 per kilometer. The Model S comes in second at 226 grams, while the BMW finishes a distant third with 385 grams. The results turn the "clean car" theory brandished by automakers and government officials upside down.

Mining and processing lithium to use in battery packs is a "high-impact undertaking," according to British magazine Auto Express. The bigger the car, the more minerals it needs to keep moving. Nissan's Leaf might have come out on top, had it been included in the study. The Model X would have probably fared even worse.

The publication also points out the study placed the Model S in the American Midwest. Putting it in a region where electricity comes from renewable sources like wind or solar would undoubtedly lower its CO2 emissions.

The researchers carefully pointed out their study doesn't mean electric cars are bad for the environment. "Both hybrid and electric vehicles are better than conventional cars in... emissions-intensive locations," said MIT's Jessica Trancik.