ARLINGTON, Va. — When it comes to protecting the environment, seniors should concentrate more on the total energy consumed in building and operating a car than its fuel efficiency — no matter how impressive it appears on the showroom window sticker.

A prime example is Toyota's Prius, a compact hybrid that's beloved by ardent environmentalists and fetches premium prices because it gets nearly 50 miles per gallon in combined highway/city driving.

Yet new data have emerged showing the Prius may not be quite as eco-friendly as first assumed — not if you pencil in the environmental negatives of producing it in the first place.

Like most hybrids on the roads today, the Prius relies on two engines — a conventional 76-horsepower gasoline engine and a battery-powered engine that kicks in another 67 horses. Most of the gas is consumed as the car goes from 0 to 30 according to alarmed Canadian environmentalists, who say Toyota's touting of the car's green appeal leaves out a few pertinent and disturbing facts.

The nickel for the battery, for instance, is mined in Sudbury, Ontario, and smelted at nearby Nickel Centre just north of the province's massive Georgian Bay.

Toyota buys about 1,000 tons of nickel from the facility each year, ships it to Wales for refining, then to China where it's manufactured into nickel foam and then onto Toyota's battery plant in Japan.

That alone creates a globe-trotting trail of carbon emissions that ought to seriously concern everyone involved in the fight against global warming. All told, the start-to-finish journey travels more than 10,000 miles — mostly by container ship, but also by diesel locomotive.

But it's not just the clouds of greenhouse gases generated by all that smelting, refining, manufacturing and transporting that worries green activists. The 1,250-foot-tall smokestack that spews out huge puffs of sulphur dioxide at the Sudbury mine and smelter operation has left a large swath of the surrounding area looking like a surrealistic scene from the depths of hell.

On the perimeter of the area, skeletons of trees and bushes stand like ghostly sentinels guarding a sprawling wasteland. Astronauts in training for NASA actually have practiced driving moon buggies on the suburban Sudbury tract because it's considered to pretty much duplicate the Moon's rocky landscape.

"The acid raid around Sudbury was so bad it destroyed all the plants and the soil slid down off the hillside," David Martin, Greenpeace's energy coordinator in Canada, told the London Daily Mail.

"The solution they came up with was the Superstack. The idea was to dilute pollution, but all it did was spread the fallout across northern Ontario," Martin told the British newspaper, adding that Sudbury remains "a major environmental and health problem. The environmental cost of producing that car battery is pretty high."

A "Dust to Dust" study by CNW Marketing Research of Bandon, Ore., shows the overall eco-costs of automotive hybrids may be even higher.

Released last December, it tabulated all data on the energy necessary to plan, build, sell, drive and dispose of a vehicle from design drawing board to junkyard, including such minutia as plant-to-dealer fuel costs, driver driving distances, electricity usage per pound of material used in each vehicle and hundreds of other variables.

To put the data into understandable terms for consumers, CNW then translated the data into a "dollars per lifetime mile" figure or the energy cost per mile-driven. When looked at from that perspective, the Prius and other hybrids quickly morphed from fuel-sippers into energy-guzzlers.

The Prius registered an energy-cost average of $3.25 per mile driven over its expected lifespan of 100,000 miles. Ironically, a Hummer, the brooding giant that has become the bete noir of the green movement, did much better with an energy-cost average of $1.95 over its expected lifespan of 300,000 miles. And it's crash protection makes it far safer than the tiny Prius.

Such information should be of major concern to senior citizens — especially those on a fixed budget.

If seniors need a small, gas-sipping car for city travel, however, the undisputed champion is Toyota's own gasoline-powered subcompact, the Scion xB, whose energy costs averaged a negligible 48 cents a mile for each mile traveled over its lifetime.

Fully armed with all the facts, they may want to zip down to their nearest Toyota dealer and trade in their Prius for a Scion xB. That would be the equivalent of reducing their energy footprint from a size 24D to about a size 5A. In the case of global warming, one small step for man may turn out to be a giant leap for mankind.

James L. Martin is president of the 60 Plus Association, a national nonpartisan senior citizen organization based in Arlington, Va.