Here we go again.

The last time Ford Motor Co. climbed into bed with the nation's leading environmental groups, it awakened to nasty protests and a seemingly incurable case of bad press.

That was in 2000 when Ford Chairman William Clay Ford Jr., awash with the possibilities of a clean start in the new millennium, announced that his company, the world's second-largest automobile manufacturer, would commit itself to achieving a 25 percent increase in the fuel efficiency of its pickup trucks and sport-utility vehicles by 2005. Ford also pledged that it would move more aggressively to clean up the tailpipe emissions of its cars and trucks.

To the outside world, that may have seemed a corporate ruse. But to people who know Bill Ford, it seemed natural enough. He long has been an odd fish among his industry peers, often swimming upstream in pursuit of environmental goals when rivals were moving in the opposite direction, or not moving at all.

So, not many people in Detroit were surprised when Ford said he would work with the Sierra Club and other environmental groups to help raise miles per gallon and lower mobile-source pollutants. But in some General Motors Corp. and Chrysler Group offices in and around Detroit -- as well as in some of the corporate suites of Ford's European and Asian rivals -- there was derision and laughter.

Bill Ford had broken one of Detroit's biggest unwritten rules, his detractors said. By starting a public relationship with Sierra Club and ideologically holding hands with other environmental groups, such as the Bluewater Network, he was cavorting with the enemy, an act bound to have embarrassing consequences for him and his company, critics predicted.

Two years later, they were proved right. A market downturn walloped Ford's earnings. Running short of cash, Ford had to back away from its ambitious plans for radically improving the fuel economy of its trucks. But demand for traditional Ford Explorer sport-utility vehicles remained high and profitable, as did demand for Ford's pickup trucks. The company sold the trucks and took the money.

The result was that Ford -- the man and the company that had done more to publicize environmental concerns than any other automobile manufacturer in Detroit -- was mercilessly attacked for "reneging" on promises to clean up its act.

The Sierra Club in June 2002 launched an advertising campaign personally targeting Bill Ford, effectively accusing him of duplicity. The Bluewater Network released print advertisements depicting the Ford chief executive with an elongated nose, accompanied by the caption: "Bill Ford Jr. or Pinocchio? Don't buy his environmental rhetoric. Don't buy his cars."

Indeed, Bluewater was running "Don't buy Ford" advertisements on its Web site as late as last week.

You'd think, after that unhappy experience, Bill Ford and his company would have learned their collective lesson. To wit: Stay out of alliances with groups that could cause more corporate harm than good. But Ford is apparently willing to take another chance with the environmental activists, this time with the introduction of a new product, the 2006 Mercury Mariner Hybrid.

The Mariner essentially is the high-end version of the Ford Escape Hybrid, which went on sale in 2004 as a 2005 model without much help from environmental groups. The Escape, with prices starting at $26,830, has done well in the marketplace, being sold through traditional new-car dealerships in the traditional way. But Ford's Mercury marketers think that the Mariner Hybrid, which starts at $29,840, needs the special help of the Sierra Club and a sales scheme that would skew most of its sales toward the Internet.

The Mariner Hybrid, according to Mercury's marketing plan, "will have a presence on the Web sites of key environmental organizations, including the Sierra Club and National Geographic [Society]." The Sierra Club also "will be working with Mercury to get the news about the Mariner Hybrid out to its members and other environmentally conscious Americans," the Mercury Mariner marketing plan says.

The logic of that approach escapes me. Were not "environmentally conscious Americans" buying the Escape? Why didn't they need the Sierra Club to reach out and touch them? Why didn't they require "personal sales consultants" -- Ford's term -- to help them buy Escape Hybrids over the Internet?

Dan Becker, director of the Sierra Club's Global Warming Program, who routinely has lambasted Ford in the past, said he is happy to be of assistance to the company in its Mariner endeavor.

"We hope that helping make the Mercury Mariner Hybrid a success will encourage Ford to invest in better technology to increase the fuel economy of its entire fleet," Becker said.

That ought to be interesting. But I'm curious about how it will all work. Maybe the Sierra Club will run one advertisement urging consumers to buy the Mariner Hybrid; but it also will run an announcement telling them not to buy the Lincoln Navigator, Ford F250 heavy-duty pickup truck or that hot-selling Ford Mustang GT.

But the problem is, without sales of those sinners, Ford won't have much money to develop and produce its saintly hybrids. But maybe it can ask the Sierra Club to help it fix that problem, too.

William Clay Ford Jr. has sought the endorsement of the Sierra Club and similar groups for the new Mercury hybrid.