Putting Rumors About Hybrids and Conventional Cars to Rest

The blogosphere is rife with reports about which vehicle is better for you and the environment. To help put falsehoods to rest, we tackled the question of whether manufacturing a hybrid results in enough greenhouse gas to outweigh the benefits of using less fuel (and emitting less carbon dioxide) once your wheels hit the road.
Most of any car’s lifetime emissions come after it leaves the dealership, not during manufacturing, we reported in the Green Guru column in the November-December issue.
Only 13 percent to 28 percent of total lifecycle emissions occur during production, whether the vehicle is a conventional car or a hybrid, Constantine Samaras and colleagues at the nonprofit RAND Corporation found. “While batteries are energy-intensive, they still comprise just a small amount of the greenhouse-gas footprint from [hybrid] vehicles,” he says.
For every gallon of gas your car burns, 25 pounds of carbon dioxide are emitted, says Jim Kliesch, a Union of Concerned Scientists senior engineer. The Toyota Prius Plugin, for instance, gets up to 60 highway miles per gallon compared with the U.S. fleet average of 21.1 mpg, producing 60 percent fewer emissions over its lifetime. [Get your car’s mileage here.]
The finding contradicts a since-debunked 2007 report concluding that the Hummer is less energy-intensive than the Toyota Prius when manufacturing is considered. Samaras calculated that the Prius battery would have to weigh more than 10 tons for the Hummer, which gets about 16 miles per gallon, to create fewer emissions.
Even a fuel-efficient conventional car would have to get at least 60 miles per gallon in order to match a plug-in electric hybrid’s greenhouse-gas emissions. So if you’re debating which kind of car to buy, hit the highway in a hybrid.
If you have environmental quandaries, send them to greenguru@audubon.org. And check out the column in the magazine.


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