DETROIT -- In 1967, when Dick Klimisch of General Motors Corp. began delving into the black art of "catalysis" as a possible cure for auto pollution, he attracted few believers.

Working in a tiny GM laboratory, Klimisch spent the next six years and $1 billion of GM's money to prove the skeptics wrong. Nicknamed "Captain Catalyst," he searched the periodic table until he found the right chemical combination to catalyze, or trigger, a reaction in the exhaust system of an automobile that rendered noxious emissions into harmless gases.

The "catalytic converter," encased in a stainless steel vessel and connected to the engine of virtually every new car since 1975, not only assured that the auto industry could comply with the ambitious tailpipe standards of the 1970 Clean Air Act. It also became the nation's most powerful weapon against urban smog -- a signal contribution still trumpeted by Detroit as proof of its ingenuity and commitment to clean air.

But the history of catalytic converters reveals another side of Detroit. The industry refined the technology only after Congress imposed strict limits and deadlines and foreign car makers threatened to develop cleaner engines. It lobbied forcefully against passage of the standards in 1970, calling them unobtainable, disastrously expensive and environmentally unnecessary. It pressed its case right up to the date of installing the first catalytic converters, and even after the devices put millions of cars into compliance, it fought to have the standards relaxed for cars and not extended to trucks.

Now as Congress attempts to strengthen the Clean Air Act, Detroit's ability to take another big slice out of tailpipe pollution is a major issue. Once again, automakers and their powerful political sponsors in Washington insist that it is not feasible or necessary and that congressional dictates to do so would be financially ruinous. They say the catalytic converter has done just about everything it can do.

To critics, it is a familiar refrain from an industry capable of changing only when forced by statutory deadline.

"We have to look at industry's arguments in light of our past experiences," said Michael Walsh, former director of the Environmental Protection Agency's mobile source program. "Their public posture is always much more pessimistic than technical reality. No place is that more evident than with the catalytic converter. As we consider the next generation of controls, we have to keep that lesson in mind."

Few experts outside the industry dispute that a new generation is needed. Cars are the primary source of ozone smog, a serious respiratory irritant created when two tailpipe pollutants -- hydrocarbons and nitrogen oxides -- are baked in sunlight.

Emissions of the two pollutants have been substantially curbed by the catalytic converter, which refined a process used since medieval times to chemically transform substances into almost everything from beer to high-octane gasoline.

But the gain in air quality has been limited because the number of vehicle miles traveled nationwide since 1970 has nearly doubled. And the explosive growth of autos projected for the next 15 years threatens to wipe out the gains altogether.

Smog is less of an acute health threat today in the most polluted cities of the 1960s, such as Los Angeles and New York, where hot summer weather drove people to hospital emergency rooms. But it is far more pervasive than 20 years ago, exceeding health standards in more than 100 cities, including Washington, and in once-pristine places such as Acadia National Park in Maine.

More also is known today of smog's withering effect on farmlands and forests as well as its role as a "greenhouse gas" that traps solar heat and raises Earth's temperature.

Nevertheless, Detroit has managed for the past decade to block tighter emission controls by wielding formidable political power.

The Big Three automakers are among the most generous congressional campaign donors, contributing $2.2 million to Senate and House candidates since 1981, according to the Public Interest Research Group. And with dealerships in virtually every congressional district and sizable plants in more than a quarter of them, the industry has a built-in grass-roots organization to pressure lawmakers.

But the industry's greatest political asset is Rep. John D. Dingell (D-Mich.), chairman of the House Energy and Commerce Committee. Dingell, whose wife lobbied for GM before their marriage in 1981 and still works in its Washington office, protects the auto interests of his Detroit district with the tenacity of a mother hen.

Dingell frequently intervenes to delay or scuttle regulations aimed at car makers, and he kept clean air legislation out of his committee during the 1980s, except when the Reagan administration tried to roll back tailpipe standards early in the decade.

Even in the current congressional battle over revising the Clean Air Act, Dingell has helped limit damage to Detroit. He agreed to sponsor President Bush's package but only after making sure it omitted the tough auto provisions of other bills, such as a second tightening of standards early next century and requirements for greatly increased gas mileage. And he maneuvered to water down Bush's most ambitious plan -- mass production of clean-fuel cars.

Automakers were not as well placed 20 years ago when Sen. Edmund S. Muskie (D-Maine) was Congress's most influential voice on clean air. Impatient with earlier anti-smog efforts, Muskie decided to force the production of clean cars by setting standards based on the health needs of cities, not on Detroit's view of what was feasible.

His legislation, passed by Congress in 1970, called for 90 percent cuts in hydrocarbons and carbon monoxide by 1975 and the same for nitrogen oxides by 1976.

It was a few years earlier that the possibility of using catalytic converters as an anti-pollution device first attracted attention. The idea came from independent suppliers of the devices to oil refineries for use in transforming petroleum into high-octane gasoline. Why not use the same catalysts to neutralize the byproducts of gasoline burned in car engines?

Detroit was not receptive. The main problem was lead, then injected into gasoline to reduce engine knock and boost octane. Industry officials argued that lead would ruin the devices. Anyway, they argued, catalytic converters would never survive the jostling they would receive in cars.

Whether Detroit gave catalysts a fair hearing is open to dispute. In 1969, the automakers were charged by the Justice Department with conspiring to delay the development of antipollution devices. The antitrust suit was settled later that year when the companies, without conceding wrongdoing, agreed to stop any illegalities.

At GM, meanwhile, interest in catalysts grew with the hiring in 1967 of Klimisch, then 28 and fresh from a job at E.I. Du Pont de Nemours and Co. experimenting with cheaper ways of catalyzing petroleum molecules into synthetic fabric for women's underwear.

In two years, Klimisch found by trial and error that a catalyst containing precious metals -- platinum and palladium -- retains enough oxygen when exposed to the high temperatures of engine exhaust to convert hydrocarbons into water vapor and harmless carbon dioxide, and carbon monoxide into carbon dioxide.

When the converter, then a vessel of ceramic beads coated in precious metals, survived an in-house road test of 50,000 miles, "We couldn't believe it," Klimisch recalled. "The conventional wisdom was that we'd never get it to last so long."

The breakthrough persuaded GM President Edward Cole to issue a historic and startling statement on Jan. 15, 1970. Speaking to the Society of Automotive Engineers, he called on oil companies to take lead out of gasoline to facilitate the use of catalytic converters in cars. Throwing down the gauntlet, he announced that starting with 1971 models, all GM cars would be able to run on unleaded gasoline.

In Washington, however, GM joined Chrysler Corp. and Ford Motor Co. in opposing standards proposed by Muskie that seemed obtainable in Klimisch's lab. Lee A. Iacocca, then Ford's executive vice president, said in September 1970 that the limits "could prevent continued production of automobiles" and "do irreparable damage to the American economy."

Opposition persisted in the early 1970s as Detroit pleaded with the EPA to suspend the standards under a waiver clause in the 1970 law. By 1973, Chrysler President John J. Riccardo called the limits still "beyond the capability of known technology." His company attempted to muzzle an independent catalyst manufacturer from lobbying for the technology by threatening loss of Chrysler business, informed sources said.

And a GM official testified at a spring 1973 EPA hearing that forcing Detroit to install the devices in 1975 models would be technically and economically disastrous.

In May 1973, the EPA agreed to relax the standards for two years. But with catalytic converters proving to be a boon to fuel efficiency and performance, GM announced six weeks later that all of its 1975 models would be equipped with the devices.

"The industry did not use good judgment in the public relations aspect of the issue," said David Cole, son of the late GM president and director of an independent auto research center at the University of Michigan.

Klimisch explained that GM did not have access until 1973 to platinum and palladium mined in South Africa to produce catalysts for millions of cars per year. He spent most of his time after 1969 experimenting with base-metal substitutes.

By 1981, after another precious metal -- rhodium -- was found to strip oxygen from nitrogen oxides and turn them into harmless nitrogen, the catalytic converter finally allowed Detroit to reach and even exceed the federal standards.

The converters, now shaped as ceramic honeycombs washed in precious metals, have been fitted in more than 110 million U.S. cars and are exported to Europe and Japan.

The devices have been so successful that Congress is considering legislation to require further reductions in tailpipe emissions beyond the 96 percent cut already attained in hydrocarbons and carbon monoxide and 76 percent in nitrogen oxides.

The industry says that while it may be able to slightly improve the converters, the target for early next century conditionally set in the clean air bill now under consideration in the Senate -- reductions of 98.7 percent in hydrocarbons and carbon monoxide and 95.2 percent in nitrogen oxides -- is not feasible technologically, and even if it were, it would cost too much.

"We can't squeeze much more out of the catalytic converter," said Klimisch, now director of environmental activities in GM's corporate offices.

As usual, feasibility is debatable. The California Air Resources Board has found that with adjustments, the catalytic converter can achieve the higher standards for up to 40,000 miles. Even the EPA acknowledges that the standards can be achieved but questions whether they are worth the increased costs; estimates range from $125 to $500 a car.

"I came out of the whole exercise with catalytic converters as a technological optimist in what the industry can do," said Walsh, the EPA's top auto pollution expert in the 1970s and now a private consultant. "When you give them a challenge, they meet it."

The first definitive link between cars and pollution came in the 1950s, when California scientist A.J. Haagen-smit traced the haze over Los Angeles to the automobile, but the few anti-smog regulations that followed were local.

The state of California in 1964 required automakers to install rudimentary emission controls on their 1966 models, asking little more than Detroit was able to achieve. The first national standards, enacted by Congress in 1966 for 1968 models, essentially adopted the California rules. But Sen. Edmund S. Muskie (D-Maine) did not think the standards were strong enough, beginning 20 years of regulatory efforts aimed at reducing automobile pollution.

1970: Determined to hold automakers responsible for smog cleanup, Muskie shepherded legislation requiring 90 percent cuts from 1970 models in emissions of the two smog-forming pollutants -- hydrocarbons and nitrogen oxides -- and a 90 percent cut in carbon monoxide, a pulmonary irritant.

The law stipulated that standards for hydrocarbon emissions of 0.41 grams per mile (gpm) and carbon monoxide of 3.4 gpm were to be achieved by 1975 models. A nitrogen oxides limit of 0.4 gpm was to be implemented in 1976 cars.

Although the tailpipe standards set by Congress that year are considered the most successful provision of the Clean Air Act, the auto industry managed to delay their implementation until a decade later on grounds of cost and feasibility.

1973: Industry pleadings persuaded the Environmental Protection Agency to relax the hydrocarbon and carbon monoxide standards for two years. The EPA set interim limits of 1.5 gpm and 15 gpm, respectively.

1974: Congress gave in to industry lobbying, agreeing to delay the 1970 standards for hydrocarbon and carbon monoxide until 1978. The EPA granted a two-year delay in the nitrogen oxides standard.

1977: Buckling again to pressure from Detroit, Congress revised the Clean Air Act, delaying the 0.41 gpm standard for hydrocarbons to 1980. The 3.4 gpm standard for carbon monoxide was postponed until 1981, with hardship waivers possible. The nitrogen oxides limit was relaxed from 0.4 gpm to 1.0 gpm and delayed until 1981 models.

1980: All new cars finally achieved the hydrocarbon standard.

1981: Despite generous waivers from the EPA, the carbon monoxide limit was met by 1981, as was the nitrogen oxides standard.

When Ronald Reagan became president, Detroit had a friend in the White House willing to support industry objectives in Congress. Although they failed to loosen requirements, Reagan administration officials and Rep. John D. Dingell (D-Mich.) worked together to head off congressional efforts to tighten the standards.