N the dim half-light of a Long Island garage, a handful of DeLoreans stand in darkened corners or suspended on hydraulic lifts, their trademark gull-wing doors ajar, their stainless-steel silver shells still ultramodern more than two decades after the DeLorean Motor Company went bust. Visible through a dusty window in the parking lot outside, perhaps 20 more DeLoreans, lined up and identical, sit waiting, like some surreal automotive dream.

This is P. J. Grady's, a modest gray automotive garage tucked behind a used-car lot in West Sayville, N.Y. As the sign on its roof - DeLorean Motor Cars - indicates, the shop specializes in the repair and restoration of DeLoreans, the famous and doomed early-1980's sports car created by John Z. DeLorean and featured in the "Back to the Future" movies.

It is estimated that around 9,200 DeLoreans were built in the car's three years of production, 1981 through 1983, and that about 7,000 are left. Of those, a good number have passed through the hands of Rob Grady, P. J. Grady's tall, thin, intensely focused owner, who has spent the past 20 years as one of the foremost of the world's few DeLorean experts. DeLorean owners from Maine to Florida send him their cars, and in a small garage that was once part of his family's General Motors dealership, Mr. Grady fixes engines, locates obscure parts, fabricates what he can't find and restores long-neglected DeLoreans so they can turn heads once more.

For many years, P. J. Grady's was about as profitable as an Edsel dealership, but that has changed. The teenagers who saw "Back to the Future" 20 years ago and were fascinated by the film's time-traveling DeLorean are now grown and seeking out the low-sweeping coupe. At the same time, the car is approaching its 25th birthday, a benchmark in the collector market. Where once values hovered around $17,000, a restored DeLorean now runs close to $30,000.

"In the last five or six years the values have gone way up," said James Espey, vice president of the DeLorean Motor Company in Houston, which bought the rights to the DeLorean brand and sells restored models. "The car is coming into its own."

It was long believed that DeLorean parts could not be found, so many cars were garaged, but Mr. Espey's firm bought the entire DMC parts inventory - everything from body panels to nuts, bolts and washers. Mr. Espey estimates that the company has enough gull-wing doors to last 120 years at the current rate of use, and enough interior carpet to cover a football field twice over. This month, the company opened a second branch near Tampa, Fla. And two shops near Los Angeles, DeLorean Motor Center and DeLorean One, serve the West Coast as P. J. Grady's serves the East.

Of the handful of DeLorean specialists, P. J. Grady's is the oldest, going back to 1979, when Mr. Grady became one of the original DeLorean dealers. For the sum of $25,000 he received the right to sell the line's one and only model, the DMC-12, and a poster of the car autographed by Mr. DeLorean, which still decorates his office, where Mr. Grady was joined on a recent afternoon by his wife, Debby, who handles the phone, and a DeLorean enthusiast named Mike Deluca.

Like many dealers, Mr. Grady signed up based on the reputation of Mr. DeLorean, who had been an engineering and marketing star at G.M. - in the early 1960's he created the Pontiac GTO, which many consider the first muscle car - and left at the height of his career to challenge the Big Three automakers. But from the start, his company was besieged with problems, starting with too little money to work with and the fact that the car, priced at $25,000, made its debut in 1981 in one of the worst economies in recent memory. "The cars were never hot sellers," Mr. Grady said.

Topping it off was Mr. DeLorean's very public arrest in 1982 for conspiracy to distribute cocaine, still a sore spot with DeLorean enthusiasts. (Mr. DeLorean was eventually acquitted; the prevailing sentiment among owners is that he was framed.) When the company filed for bankruptcy protection that year, Mr. Grady continued to honor his customers' service warranties. Over time, he found himself doing more and more repair work on DeLoreans, until that was all he did.

Not surprisingly, he has developed an affection for the car, though it is a cool, dispassionate one, tempered by years of daily involvement. "It's a good car," he said simply.

Mr. Deluca, hovering nearby, said: "Rob is being modest. He's completely dedicated. I was driving by once and it was Easter Sunday. It was freezing. Rob was out in the parking lot testing temperature sensors."

IN a far corner of the garage, the P. J. Grady's mechanic, Pat Tomasetti, stood in blue coveralls beneath a DeLorean on a hydraulic lift, draining oil and listening to NPR. Mr. Tomasetti has been repairing and restoring DeLoreans at P. J. Grady's for 13 years and is accustomed to overenthusiastic fans of the car. He laughed as he recalled the time a Japanese man showed up with his family, saying he had flown to America to visit Disney World and P. J. Grady's.

The DeLorean Mr. Tomasetti was working on had come in from Pennsylvania and was set to have its front fender replaced, among other repairs. Another DeLorean, its door crunched like a soda can, was in need of extensive body work. Outside, dozens more waited, a daunting workload for two men.

"I'd like another mechanic, but it's hard keeping them," Mr. Grady said. "Most guys don't like doing restoration work. It's dirty, and there's also the repetition."

People who spend time around garages tend to acquire a detailed know-how of car design and mechanics, but DeLorean experts take specialization to a refined level. Because of its unpainted stainless-steel body, the DMC-12 was available in only one color, silver. Its interior was black leather or gray leather, nothing else, and the car changed little over its brief production run.

So while the Corvette aficionado has a half-century of paint schemes, body types and fancy options to ponder, the DeLorean lover must be content with trivial changes - the radio antenna on the '81 models is in the windshield, for example, while on the '82 it is on the left rear quarter.

Pointing to a model whose license plate read BK2DFUTR, Mr. Grady proceeded to make the indistinguishable cars distinguishable. "We just got this one out of mothballs," he said. "It sat for four years. The owner decided to sell it. It only has 11,000 miles."

He continued: "That one over there was in a wreck. Needs a new door." Then he walked over to a car covered in a soft blanket of dust. The passenger window was stuck halfway down, and the seat was given over to orphaned parts. Mr. Grady's pupils widened, as if he were laying eyes on a DeLorean for the very first time. "This is the 530," he said reverently. "It's a Legend prototype, Twin Turbo. They only made three of these."

The 530 is going to be restored as his own DeLorean, Mr. Grady said, just as soon as he finds the time. "Sometimes you get a little burned out," he mused, reflecting on the vagaries of being a DeLorean expert. "Then something rejuvenates you."