NEW YORK (CNNMoney.com) -- Winning "Best of Show" at the annual Pebble Beach Concours d'Elegance car show, taking place this weekend in California, can add 50 percent or more to the value of a collectible car, one that's already worth hundreds of thousands, if not millions, of dollars.

But that's not why collectors enter their cars.

1937 Delage D8-120 S Pourtout Aero Coupe

"It's about bragging rights," said Craig Jackson, president of the auto auction company Barrett-Jackson. In fact, Jackson said he can't even remember a winning car ever going on to be sold at auction in the past 15 to 20 years.

Along with the Meadowbrook Concours, which took place in Michigan earlier in August, and the Amelia Island Concours, which took place in Florida in March, Pebble Beach is part of the "Triple Crown" of collector car shows. But Pebble Beach is the Kentucky Derby. It's the big win.

This year, only 175 cars will compete in the invitation-only event, down from 225 last year. The cars will be judged in 25 finely-tuned categories with names like "Pre-war Delahaye," "Post-war Delahaye" and "American Classic Open, 1932 - 1941."

Photos: The (re)making of a winner: 1938 Horch 835A Erdmann and Rossi Sport Cabriolet

"A lot of these cars are rolling sculptures never to be duplicated again," said Rob Myers, founder of RM Auctions, an auction company that also restores collectible cars.

Aside from the cost of buying a high-end collectible car, restoring a car to a competitive level can cost anywhere from hundreds of thousands to a million dollars.

"I work on rich men's toys," said Bob Smith, who operates Bob Smith Coachworks, a Texas company that specializes in restoring classic Ferraris. "I work for some people who have three more dollars than God."

The cars Smith has prepared for past Pebble Beach shows include one category-winning Ferrari race car valued at $22 million.

Still, for those coming to this show, all agree that it's not about money. It's about "passion." It's just that to fulfill the passion happens to require lots and lots of money.

For a car that's in poor condition, restoring it can mean literally tearing the car apart, replacing major and minor components and rebuilding the car in a process that commonly takes years.

Simply cleaning the car right before the show, a job for which there are highly experienced professionals, can cost as little as $100 or as much as $3,000, said Myers. In the industry, it's knows as "detailing" and comparing it to a typical car wash is like comparing an aluminum toolshed to Xanadu.

The process involves specialized substances for each different surface on a car - painted surfaces, copper surfaces, nickel-plate surfaces - and a gentle touch to prevent "burning" an original paint job that could be more than half a century old.

These days, collectors don't like cars that have been "over-restored," meaning they're made to look so good it's literally unreal.

"What's important and popular today is originality," said Dick Messer, executive director of California's Petersen Automotive Museum.

Messer attends the event every year both to show cars from the museum's collection - this year he brought a 1952 Ferrari originally owned by Henry Ford II - and to meet with friends and museum supporters.

The Ferrari was in nearly perfect shape, he said, but had a few wrinkles in the body, a natural flaw that will occur in an older aluminum-bodied car that's seen some use.

For cars that are still in good shape, the goal is actually to keep as much of the original car intact as possible in what's called a "preservation restoration" said Myers. That includes keeping the original paint job. "On a great original car it's almost criminal to restore them," he said.

In order to keep the appearance as original as possible, Myers said, he has even replaced torn leather upholstery on a classic car with leather that his shop deliberately worked over so that it would look worn.

Still, many of the cars at this year's show will have that "better than new" appearance.

"Back in the 20s, 30s, and 40s, they didn't have a paint like that from the factory" Messer commented. He spoke by cell phone from the seat of the Ferrari as he watched cars drive past on their way to the 60 mile drive that kicks off the event.

For car enthusiasts who can afford the pricey hotel rooms, Pebble Beach weekend, with the high-end car auctions, parties and vintage races that surround the main event, is the biggest weekend of the year.

"I would rather miss Christmas than miss Pebble Beach," said Smith.

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