The upcoming documentary “American Dreaming” features the designers who worked for Detroit’s automakers from 1946 to 1973. Watch the trailer for the film, which does not have a release date, above. Video by Jim Toscano and Danny Gianino of Freeage Productions.

Norbert Ostrowski began designing cars during the golden age of the American automobile. For 30 years, he worked in the styling departments of Detroit’s iconic brands: Chrysler, General Motors, AMC. But his sketches no longer exist. Like most of the early-stage artwork created by America’s auto designers, they’ve been destroyed.

Enter art collector Robert Edwards. The lifelong car enthusiast has curated the most comprehensive showing of those designs, spanning from 1946 to 1973. The exhibit, “American Dreaming: Detroit’s Golden Age of Automotive Design,” opened last week at Lawrence Technological University in suburban Detroit.

Featured in the collection is one of Ostrowski’s early sketches of an AMC Matador that Edwards found for sale in Ann Arbor. Ostrowski, now 77, recognized it immediately, Edwards said.

“His exact words were, ‘how the heck did that get out?’”

The designs were never meant to leave the studios. Automakers routinely destroyed early sketches for fear they would fall into the wrong hands.

But some of them made their way out of Ford, GM and Chrysler, as well as now defunct Studebaker, Packard and AMC. According to one designer, they were smuggled out in boxes with false bottoms. One employee famously hid his sketches inside the liner of his trench coat. “As an artist, you would hate to see your artwork destroyed,” Edwards said.

Now they exist in attics and garages in the homes of the artists and their relatives. That’s where Edwards finds them. He’s been collecting these “bootleg” sketches for years, buying them from estate sales all over Michigan.

He calls the artwork the story of mid-century modern design in America.

“The car is such a part of the American psyche,” Edwards said. “It’s possibly the most important industrial object ever created. It has touched everyone’s life.”

Exhibit co-producer Greg Salustro said the designs harken back to a time when America thought anything was possible.

“This is the age that America thought they could overcome racism, land a man on the moon, win the Cold War,” he said. “This exhibit reflects this unbridled exuberance that took place at the time.”

Aside from the exhibit, the two auto enthusiasts are also co-producing a documentary called “American Dreaming.” It features interviews with the men and women who influenced mid-century American design and shaped the way we remember the golden era of the automobile.

It’s also a love letter to Detroit.

“This is a Detroit story,” said Salustro. “It’s about how Detroit inspired a nation.”

Just as the automakers jumped back into production in 1946 after its years supporting the Allied forces, today Detroit is determined to rebound after decades of decline and an unprecedented municipal bankruptcy, he said. “We want Detroit to be proud of its artistic heritage.”

See more photos of the innovative artwork that escaped the shredder:

Captions by Robert Edwards. Learn more about the upcoming documentary “American Dreaming”: Americandreamingfilm.com. Here you can also find out how to support the film, which is not yet complete and does not have a release date.