Don Harold, a subway aficionado who sometimes used subterfuge to save vintage train cars from the junkyard — cars that are now among the star attractions of the New York Transit Museum in Downtown Brooklyn — died on June 14 in a nursing home in Bayside, Queens. He was 91.

Thomas Jablonski, a close friend, said the cause was congestive heart failure.

Mr. Harold, whose maternal grandfather was a Brooklyn trolley motorman and inspector, adored the hulking relics that once rumbled and screeched on subway and elevated tracks.

To him, they were as essential a part of New York’s history as the Statue of Liberty.

“When she was falling apart, they fixed her,” he said in an interview with The New York Times in 2003. “You don’t sell her for scrap.”

He got his chance to save train cars when he was hired in 1965 in the public affairs office of the city’s Transit Authority. His supervisor already knew about his passion for the old rolling stock and felt that he could be an effective preservationist.

“I think that I could get that done, but you don’t want to know how I would do it,” Mr. Harold said he told his boss, according to an obituary posted by the Electric Railroaders Association.

Eleven years later, during the Bicentennial, Mr. Harold’s efforts helped lead to the creation of an exhibition that included 15 restored cars at the decommissioned Court Street subway station in Brooklyn. It was intended as a short-term exhibition, but it proved so popular that it was frequently extended and finally rechristened a museum in 1989.

“He was the patriarch of the museum,” said Concetta Bencivenga, the director of the museum, which has nearly 100 vintage cars in its collection, more than 20 of them at the museum and the rest in storage yards. “All the cars are here because of the work Don did.”

To save the cars that the Transit Authority did not volunteer for restoration, Mr. Harold deployed a network of workers within the agency, some of whom he had met through the BMT Holy Name Society, a religious group of train workers, before he joined the agency.

The cars had to be overhauled electrically and mechanically to make them trackworthy again; Mr. Harold was known for making sure the interior and exterior colors were accurate, Mr. Jablonski said, and he had reproductions of period advertising and old maps added to the cars.

The Times called Mr. Harold and his preservation-minded colleagues a “tiny guerrilla army” that “bent the rules, disregarded orders and played hide and seek with subway cars sentenced to execution.”

The group employed various tactics.

“Through his cohorts, he would hear which cars were on the extinction list, and they would change the numbers so they couldn’t be found,” Mr. Jablonski, the deputy chief of strategic capital planning of the Metropolitan Transportation Authority, the Transit Authority’s parent, said by phone. “So car number 2390 became number 2590, and it would be tucked away in a yard.”

One of those Mr. Harold helped save, an old BMT car with cane seats and ceiling fans, bore the telltale signs of his group’s trickery.

“When the guys finally sanded it down to restore it for the museum,” he told The Times in 2003, “they said, ‘Hey, what’s going on? We found five different numbers on this thing.’ And I said, ‘That’s five times they tried to scrap it.’”

One day in the mid-1960s, Mr. Jablonski said, Mr. Harold heard that a contingent of Transit Authority managers was heading to a storage and maintenance yard in the Bronx to locate five early-20th-century IRT Low Voltage cars to scrap them. But Mr. Harold wanted them restored, as five other such cars had already been.

“Don calls someone in charge of moving cars and says, ‘Move those cars out of there,’” Mr. Jablonski said. They were temporarily moved to a track south of Pelham Parkway until it was clear that they were out of danger, when they were returned.

“Don got as big a kick out of pulling a fast one as he did saving the cars,” Mr. Jablonski said.

Donald William Harold was born on Aug. 18, 1931, in Brooklyn. He was raised by his mother, Marie (Muessig) Harold, who worked at a department store, and his maternal grandparents. His father, Chester, left the family when Donald was a toddler.

When Don was 17, he expressed his interest in mass transportation in a letter to the editor of The Brooklyn Eagle, criticizing a city plan to replace trolley cars, like the one his grandfather had operated, with buses on 10 Brooklyn lines.

“People are packed in buses like sardines,” he wrote. “The buses are too small for the number of people riding them. Even though the trolleys may be old, they can still hold their own if given a fair trial.”

Mr. Harold held several jobs before joining the Transit Authority. Perhaps most important, he operated a trolley as a teenager in Brooklyn — illegally and with the help of a friendly motorman, he told Mr. Jablonski — and later got a legitimate job running one in Atlantic City in the 1950s.

He was also a salesman in a record store, a bank teller and an I.R.S. examiner. In 1968, he received a bachelor’s degree in economics from Saint Peter’s College (now University) in Jersey City, N.J.

Mr. Harold eventually left the Transit Authority’s public affairs office to run its employee suggestion program. He retired in 1986. He never had a job at the Transit Museum, but he was a consultant there and was sometimes referred to as its curator and co-founder.

He leaves no immediate survivors.

The lore of Mr. Harold’s preservation work includes a story about the planning of the 1976 Bicentennial exhibition. Mr. Harold received enough cooperation from the Transit Authority to restore one vintage car from each of several significant train classes, but when he was told that the rest of the cars would be scrapped, he thought quickly.

“He said, ‘No, no, no, we’re having Nostalgia Rides,’” Ms. Bencivenga recalled — in other words, Mr. Harold saved the cars by spontaneously conceiving an attraction in which passengers would board restored trains for rides on designated subway routes around the city.

“And this is what happens today,” Ms. Bencivenga said. “We’ll take the R-1/9s to the Rockaways, and when we go to Yankee Stadium we’ll take the 1917 IRT Lo-V’s.”