On the surface, almost everything about the Toyota Prius seems great. It has been named the Green Car of the Year for the last five years by Consumer Reports and gets 46 miles per gallon according to the EPA.

With high gas prices, the hybrid appears to be a great way for a driver to be friendly to the environment and lower her carbon footprint.

While drivers such as environmentalist Laurie David who like to flip off Hummer drivers may have their hearts in the right place, one study said her middle finger has been aimed in exactly the wrong direction.

In May, CNW Marketing Research’s second annual “Dust to Dust: The Energy Cost of New Vehicles From Concept to Disposal” report concluded that the overall environmental impact of the Prius is significantly higher than many SUVs and other nonhybrid cars.

This was because the study found that an automobile's fuel economy is not the largest factor in its impact.

Prius Vs. Other Hybrids, Trucks

The study added up all energy needed to design, build, ship, drive and dispose of a vehicle throughout its lifetime. CNW translated the data into a energy-dollars-per-lifetime-mile figure. According to the study, the Prius costs $2.19 per mile over its expected life span of 100,000 miles, which is down from $3.25 in the 2007 study.

But the newer study still shows 156 cars with lower per mile cost than the Prius, including pickup trucks and SUVs such as the Toyota Tacoma ($.97), Jeep Liberty ($1.11), Ford Explorer ($1.87), Dodge Durango ($1.69) and Jeep Wrangler ($.65).

Still, Toyota's showpiece fared much better than other hybrids like the Civic Hybrid ($2.94), the Camry Hybrid ($3.42) and the Accord Hybrid ($4.28).

Questioning The Study

There have been many critics of the study, most notably the Pacific Institute, which criticized the report for not releasing its full methods, assumptions and data to peer review.

The Pacific Institute also disagreed with CNW's '07 average life span estimate of 109,000 miles for the Prius which, if changed, would dramatically change the results.

Art Spinella, President of CNW, said the surveys for the original study found that Prius drivers were averaging 6,700 miles a year because many households were using it as a second car. that meant it would take 15 years to get to 100,000 miles.

Spinella said the newest study showed that Prius drivers now average over 11,000 miles per year, which was a factor in lowering its cost-per-mile.

Batteries Add To Impact

One factor that increases the size of the Prius and other hybrid's cost-per-mile is their batteries. Prius batteries are made of nickel and are much different from the acid-based ones in regular autos.

Each of the 1 million Priuses sold in America has a battery that contains 32 pounds of nickel. According to the Sierra Club, that accounts for about 1 percent of all the world's annually mined nickel. The environmental cost of mining the nickel is significant, and the cost of recycling the nickel batteries is significant because there is not a massive industry, as there is for regular batteries.

"The cost, especially for hybrids in general, is, what do you do with the batteries when they are done?" said Spinella. "There have been some advances made, but for the most part, the aftermarket or disposal part of the process, they're still not sure what to do with them."

Toyota currently accepts Prius batteries for recycling, and the company issues warranties on them for eight years or 100,000 miles. Toyota's Web site says the company is studying the possibility of remanufacturing the recycled batteries.

Tire Trouble

Another possible environmental problem with the Prius is reported tire wear. CNW studies said that a Pruis' tires last one-quarter the distance of those on a Corolla. A quick Web search of the words "Prius tire wear" brings up dozens of blogs and postings from Prius owners complaining of excessive tire wear.

So while the study found some reasons for hybrids having a large carbon footprint, how is it possible that it could find gas-guzzling SUVs to have a lower one? In the first study, CNW found that the Hummer had a lower dollar per mile cost than the Prius. The new study found the opposite, and Spinella said that is because people are now driving their Hummers fewer miles because of the cost.

The top factor in determining a car's environmental cost-per-mile, Spinella said, is its recyclability. Because hybrids are newer technology, their parts are less reusable in other makes and models.

"That's why something like the Hummer winds up being so low a cost … all of the technology is really spread among many, many different vehicle lines," he said.

That is a reason CNW found the Jeep Wrangler to have the fourth lowest cost-per-mile of any automobile on the market, even though it averages 15 miles per gallon in city driving.

"It's just a simple product," said Spinella. "The glass is easy to make. There are virtually no compound curves in the whole vehicle. The doors, for example, are removable and far cheaper than trying to do the conventional hinge thing. A lot of models don’t have roll up windows."

Overall, the CNW study found that newer technology, while it may be environmentally friendly in theory, can do more harm than good until the technology becomes more widespread. Technology produced on a mass scale for one single product costs more energy than a massed produced product that goes toward dozens. The Prius' environmental cost-per-mile has fallen from the first study, and CNW believes it will continue to fall.

"Generally, what we're seeing now is the Prius is becoming more mainstream, which is not what a lot of the owners like, but that's life," said Spinella. "And so the cost-per-mile comes down because you're advertising over higher volumes and across different platforms."