6 most expensive cars for auction at Pebble Beach Concours

The Pebble Beach Concours d'Elegance started in 1950 with a small group of enthusiasts showing off their cars around a golf tee. It's since become a big-money circus for rich car collectors—part Academy Awards, part art auction, part launch pad for global carmakers and part theme party for millionaires and billionaires.

Yet the chief spectator sport at Concours is auctions. More than $400 million worth of cars are being sold through Sunday—including what is likely to be the most expensive car ever sold at auction.

The previous record was a Mercedes-Benz racer that sold last summer for $31.6 million, including auction fees.

Click ahead to see the top cars to watch, along with their expected sales prices. Estimates are courtesy of Hagerty, Gooding & Co., and RM Auctions.

—By CNBC's Robert Frank
Posted 14 Aug. 2014

(Cover image: This 2006 Ferrari FXX Evoluzione will be auctioned off by RM Auctions for an estimated $1.7 million to $2.1 million and is one of a select few "hypercars" designed for ultimate speed and performance.)

Estimate: $50 million-$75 million
Auctioned by: Bonhams

Ferrari GTOs are the holy grails of car collectors, and they rarely come up for auction. This 1962 Ferrari 250 GTO was the 19th made, and was part of a famous collection in Italy owned by Fabrizio Violati.

Even if this car sells for anywhere near its low estimate, it will become the most expensive car ever sold at auction.

Estimate: $25 million
Auctioned by: RM Auctions

Ferraris dominate the top of the auction lists now just as they've dominated the racing world for much of the postwar era. And this Ferrari is one of the greats. As RM Auctions said in its marketing materials, this car is "exceptionally rare, fast, and achingly beautiful."

Ferrari built only three of these cars and this was the first one built. It was fitted with a super-lightweight aluminum bodywork, a Tipo 563 chassis constructed of smaller and lighter tubes, and 70 additional horsepower compared with the standard 275 GTB, which made it "the most formidable weapon in Ferrari's competition arsenal," according to RM Auctions.

It also shows that great Ferraris don't always have to come in red.

Estimate: $12 million to $14 million
Auctioned by: Gooding & Co.

Among auto aficionados, many regard the McClaren F1 as the first true supercar—and still one of the best.

This 1995 F1 has 627 horsepower from a 6.0 liter, V-12 engine. An F1 set the record for world's fastest production car at 240 mph in 1998. But the buyer isn't likely to drive it. This F1 has only 1,004 miles on it. Also cool: The engine has a gold-foil heat shield.

Estimate: $10 million
Auctioned by: RM Auctions

The Ford GT was a legend on the racetrack, and proved that Detroit could make cars to rival Ferraris in endurance racing.

The GT40 was one of just six open-top GT40 roadsters built, and this specific car was used as a promotional and development car by Shelby American, the performance-car builder and modifier formed by Carroll Shelby.

Ford GT40s are especially valuable to collectors because of their race history. They won four consecutive victories at the 24-Hours of Le Mans. Henry Ford II sat in this particular GT40 with Carroll Shelby at the wheel in 1965 on the tarmac of Los Angeles airport.

Estimate: $5 million to $7 million
Auctioned by: Gooding & Co.

Even before James Bond came along with his DB5, Aston Martin was famed for its style, speed and English reserve.

Aston Martin built only 20 DB3S models and only 16 survive. They were strong racers on the track and this car is among the most authentic in existence.

This one was rebuilt, repainted and re-trimmed by Aston Service Dorset in 1990 and dutifully maintained by its owner.

After it was sold to a New York collector, it was looked after by top car restorer Paul Russell of Essex, Masschusetts. The car has plaid seats and finished in a period-correct, racing green.