Someone has paid $3.74 million for the star of the most celebrated car chase in film history — the 1968 "Bullitt" Mustang GT driven by Steve McQueen over the streets of San Francisco.

It's the largest price ever paid for a muscle car.

The iconic Ford crossed the auction block Friday at Mecum Auctions in Kissimmee, Fla., during the world's largest collector car auction. The winning bid was $3.4 million, but auction fees ramped the total up to $3.74 million. The buyer's name was not disclosed

McQueen's legendary car was long thought to be lost and rusting away in some forgotten junkyard. But in 2017, nearly a half century after it disappeared, it resurfaced.

Actually, it was never lost; it just kept a low profile.

In 1974, a New Jersey insurance executive named Robert Kiernan was shocked to see the car offered in a classified ad in Road & Track magazine, according to Vanity Fair. The 390-horsepower V-8 in Ford's Highland Green paint still had the original movie camera mounts and a hole in the trunk for a smoke machine.

Kiernan paid $6,000 so he could use the souped-up piece of cinematic history as his daily driver.

"It was unbelievable — I mean, we had seen the movie, and then to see the car," Kiernan's wife, Robbie, told CBS News.

McQueen eventually tracked down the car and twice tried to buy it back, but Robert Kiernan wasn't interested.

Vanity Fair's Brett Berk writes that Kiernan drove the Mustang for about six years, adding 30,000 miles to the odometer before the clutch gave out in 1980. He then retired it to a garage on the family's property.

Kiernan, who died in 2014, never drove it again.

But with the film marking its 50th anniversary in 2018, Kiernan's son, Sean, decided to get the car in driving shape again. But it still retains the original finish, now an oxidized patina with a smattering of rust spots.

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There were actually two identical Mustangs in the 1968 film. The Kiernans' was the "hero car," which is shown throughout the film and was driven by McQueen mostly in casual driving scenes.

The other car was the "jump car," or jumper car, used for the dramatic chase scenes. That's the Mustang you see catching air on a steep section of Taylor Street between Vallejo and Filbert streets, and landing violently as it careens downhill.

The jump car was recently found in a scrap yard in Baja California, according to the Los Angeles Times. It has been restored.

As for the "hero" Mustang, Robert Kiernan's decision to hold on to the car and not sell it to McQueen turned out to be a wise move.

The car was expected to fetch between $3 million and $5 million. The selling price of $3.4 million might seem to be on the low side, but the classic car market has softened in the last two years.

This article is an updated version of a story that previously appeared on SFGATE.

Mike Moffitt is an SFGATE Digital Reporter. Email: moffitt@sfgate.com. Twitter: @Mike_at_SFGate.