When Abraham P. Korotki, a suburban Baltimore attorney, bought his flossy white, fully loaded 1976 Cadillac Eldorado convertible in August 1976 for $16,250, he thought he had made a smart move.

After all, America's long romance with convertibles was sputtering out. General Motors in Detroit was pushing its 1976 model as the "last convertible in America," Korotki said, and it seemed destined to become a precious collector's item.

But GM suddenly resumed production of convertible Cadillacs seven years later in 1983, riding the crest of popular demand among Americans for rag-tops. Korotki says the value of his '76 Eldorado went down, and his temperature went up.

He sued GM. Joined by fellow Cadillac convertible owner Richard K. Adolph, a local chiropractor, Korotki demanded that GM compensate them and all other '76 Cadillac convertible owners, some 14,000 people across the country, for their alleged monetary losses.

In the lawsuit, filed in federal court here, the two men contend GM embarked on a fraudulent advertising campaign, deliberately misrepresenting the '76 convertible as the "last of the breed" and a "priceless collector's item" and luring thousands of buyers with "cavalier campaign promises."

GM attorneys countered that the lawsuit was vague and contained no evidence that GM intended, as part of a fraudulent scheme, to resume convertible production after the 1976 model year.

Attorneys for both sides argued the case this week before Chief U.S. District Court Judge Frank A. Kaufman. The judge indicated he will rule later after attorneys submit further pleadings.

In a telephone interview today, Korotki, 38, said he bought his '76 Eldorado convertible for $16,250 "because it was a hot item." The car had a list price of $11,049, "but the dealers were getting whatever they wanted," he said, because of GM's "last convertible in America" campaign.

"I thought I was getting a bargain at $16,250," Korotki said. "Some were selling for $20,000 and up." Though he viewed the car as a potential collector's item, he said he drove the car "back and forth to the beach," running up about 30,000 miles between 1976 and late 1983. "It was in excellent condition," he said.

When GM announced plans to resume convertible production last year, Korotki filed his lawsuit, then sold the Eldorado for $10,000 to another attorney at a loss he says is difficult to calculate.

Korotki's lawsuit comes after a roller coaster career for the convertible car in America. Production of the popular style peaked in 1965 at 509,415 cars by GM, Chrysler, Ford and American Motors. It then plummeted, falling to less than 76,000 by 1971. Industry analysts blamed the decline on air pollution, air conditioning, government regulations and high-speed freeways, which made the hair-in-the-wind thrill of an open car a bit hectic for some.

American Motors stopped convertible production in 1968, followed by Chrysler in 1971, Ford in 1973 and most of GM in 1975. With considerable fanfare in April 1976, GM announced that Cadillac would roll the last 14,000 American-manufactured convertibles off its production line that year, prompting a flurry of collector-item sales. The last 200 were decorated with special red-white-and-blue Bicentennial plaques.

Some collectors kept their convertibles, undriven, in undisclosed garages. Others hired security guards to protect their prizes. GM offered the very last convertible to the Smithsonian Institution, but was turned down.

After a six-year hiatus, consumer interest in convertibles revived, and in 1982, GM's Pontiac division resumed production, turning out 1,400 rag-tops. Ford, as well as GM's Buick, Chevrolet and Cadillac soon followed. By mid-1983, convertibles comprised 2 percent of new car sales in the United States, according to industry sources.