By BILL VLASIC and NICK BUNKLEY Published: October 25, 2008

IN late May, senior executives at General Motors confronted a decision that few thought they would ever face: whether to continue developing the next generation of one of the most successful products in G.M.’s 100-year history - the full-size sport utility vehicle - or to punt the program entirely.

Peter Wynn Thompson for The New York Times

With the plant’s pending closure, Joseph Murwin is moving to Kansas. More Photos »

It’s rare for an automaker to pull the plug on high-profile initiatives, much less one involving a $2 billion, top-to-bottom overhaul of a high-volume vehicle that once helped it rake in cash.

This was also G.M.’s flagship platform, code-named CXX, which would underpin popular models like the Escalade, Yukon and Suburban, brawny tanks that had defined the auto giant’s image for more than 15 years.

The executives killed the CXX project without a single dissenting vote. And with that, the era of the big S.U.V. was as good as dead, done in by soaring gasoline prices and consumers fleeing to smaller, more fuel-efficient cars.

"It would have been very difficult in today’s environment to spend a couple of billion dollars to do a replacement," said Robert A. Lutz, G.M.’s vice chairman and head of product development. "Reality had set in."

G.M.’s reality is, indeed, a harsh one.

After losing $18.8 billion in the first half of this year and facing more red ink for months to come, G.M. is now trying to salvage its future through a possible merger with Chrysler, another deeply troubled American automaker.

Amid the financial crisis and the chaos on Wall Street, the struggles of G.M., the world’s largest automaker, have been just another startling development in a season chock full of startling news.

Yet it is an epic moment. Autos have been prized jewels in America’s industrial crown for the better part of a century, and Detroit once dominated a truly global industry. Now, possible bankruptcy looms for G.M. and perhaps Chrysler.

As of Friday, shares of G.M. were down 76 percent for the year and Ford shares were down 70 percent. While American automakers are certainly the victims of their own missteps, the broader economic downturn is now working against them as well. Even Toyota, the mighty Japanese automaker, announced on Friday its first quarterly drop in sales in seven years.

Like the nation’s banks, Detroit automakers are pushing for the federal government to use taxpayer money to rescue them from their mistakes, but it is uncertain how much Uncle Sam will aid the industry.

What is clear is that Detroit, among its other miscues in recent years, particularly overindulged its romance with S.U.V.’s, leaving it tethered to a product line that may prove to be the industry’s undoing.

For its part, G.M., once admired as "the General" of the global auto industry, has been pushed to the brink of collapse. Besides its mating dance with Chrysler, G.M. has taken other bold steps to try to reverse a slide that analysts say is causing it to burn through an estimated $1 billion in cash each month.

Within days of its decision to abandon the CXX program, G.M. announced another round of North American plant closures, including the planned shutdown of its sprawling factory in Janesville, Wis., where the big S.U.V. was born in the early 1990s. G.M. has promised to carve an additional $10 billion of its costs in a frantic effort to preserve its dwindling cash. It’s a far cry from the glory days of S.U.V.’s, when their sales fueled fat profits for G.M. and its rivals, Chrysler and Ford.

"For a long time, gas was cheap and money was easy and Americans wanted these big vehicles," said John Casesa, a principal in the Casesa Shapiro Group, the auto consulting firm. "There was no downside - until the bottom fell out."

GENERAL MOTORS lived off its S.U.V.’s and pickup trucks since they were introduced, and made one last, huge investment in new models that hit the market two years ago.

In fact, the company accelerated development of those vehicles to offset otherwise shrinking revenue.

But in retrospect, G.M. made one bet too many on the market for S.U.V.’s., whose sales have tumbled more than 30 percent this year and have been in decline since 2004. All of the Big Three have had to close plants, lay off thousands of workers and take substantial charges to cover the declining value of S.U.V.’s coming back to dealers from expired leases.

Although even top-tier automakers like Toyota have been stung by the falloff, G.M., the biggest producer of full-size sport utilities, has been hurt the worst. The impact hit home two weeks ago in Janesville, a city of 64,000 about 75 miles southwest of Milwaukee.

On Oct. 13, G.M. announced that its 90-year-old plant there, the company’s oldest factory in the United States, would build its last S.U.V. just before the Christmas holidays.

Just a year ago, the Janesville plant was churning out 20,000 Suburbans, Yukons and Tahoes each month. As the assembly lines wind down, the plant is now producing less than 100 S.U.V.’s a day.

Only 1,200 employees remain from a work force that once numbered 5,000, and the end is drawing near.

The workers there are stunned by the plant’s sudden demise. After building 3.76 million S.U.V.’s over the last 18 years, Janesville is headed for the automotive scrap heap.