Are hybrids manufactured in a green way?

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In 2007, marketing research think tank CNW rated all model cars sold in the United States in 2005. Rather than simple miles per gallon ratings, the controversial report considered the energy used by each car, from the concept stage to the junkyard. Previously overlooked details like the energy used to ferry the design engineers to and from work each day, create replacement tires and build car materials were all factored in over each vehicle's lifetime.

The study also considered the energy that went into designing, manufacturing, assembling, transporting, selling, purchasing, driving, maintaining, repairing and ultimately scrapping a car. These energy inputs were quantified as a cost per mile driven over the life of the car, expressed in dollars.

The final results were startling. Behemoths like the Cadillac Escalade, Land Rover and even the Hummer H3 required less energy over their lifetimes than any hybrid vehicle considered. Could it be that a Hummer -- the emblem of scorn among environmentally conscious drivers -- was more eco-friendly than the hybrids themselves?

The results were clear. CNW measured the environmental impact of a Hummer H3 at $1.949 per mile, while impacts for hybrids like the Honda Insight and the Toyota Prius came to $2.94 and $3.25, respectively [source: CNW].

What happened to the hybrids? The study highlighted some factors that make them energy efficient on the consumer end, but have big environmental impacts in the hands of manufacturers. For example, the technology responsible for the electric battery that makes hybrids fuel efficient and helps them emit less greenhouse gases is relatively new. Materials also have to be found and transported. As a result, battery production isn't as streamlined as it would be for the standard internal combustion engine [source: Will].

The low estimated total mileage for the hybrid also hurt. The estimate for total miles over the lifetime of the Insight, for example, was 109,000 miles (175,419 kilometers) -- comparable to other hybrids [source: CNW]. As a result, heavy energy inputs frontloaded into the early life of the car isn't divvied out in a hybrid as it is in the H3, for example, which is expected to get 207,000 miles (333,134 km).

The study also considered the lower lifespan of the hybrids. While parts and mechanics needed to repair standard engines are abundant and relatively cheap, this wasn't the case with hybrid technology in 2005. The authors likened the lifespan of hybrids to those of cheap desktop printers: It makes more sense to simply throw away an old printer and replace it with a new one, since the cost of repair would be as much or more than the cost of replacing it. In CNW's estimation, landfills were piling up with both printers and hybrid car parts -- which could spell disaster for an eco-friendly product like a hybrid.