Richard Petty's once lost NASCAR Plymouth Superbird is heading to auction and the sky's the limit

The Plymouth Superbird may have been a one-year wonder, but it remains a classic today.

The aerodynamically-optimized muscle car was built for NASCAR’s superspeedways, where Richard Petty and others competed in it during the 1970 season before it was effectively banned from competition the following year.

Petty won 18 races that season driving Superbirds and Plymouth Road Runners, but finished fourth in the standings behind season champion Bobby Isaac, who used the similar big wing Dodge Daytona on the fast tracks.

But it's Petty’s iconic blue ‘Birds that are among the most famous American race cars of all time, and one will be crossing the block at the Mecum Auctions event in Harrisburg, Penn., on Saturday, Aug. 3.

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It’s the crown jewel of a more than 40-strong car and motorcycle collection being offered by prominent collector Todd Werner, which includes the Road Runner Petty won the Daytona 500 in during his 1971 championship run and several classic drag cars worth high six to seven figures each.

When Werner bought the Superbird over a decade ago, he wasn’t even sure exactly what he paid for. Petty had converted it into a Road Runner for 1971 before selling it midseason to fellow racer Doc Faustina, who later put a Dodge Charger body on it that it wore in various series until being retired in 1976.

A few years after he purchased it, Werner met Petty and told him about the car. The King was intrigued and had him send it to his shop in North Carolina so the team there could try to figure it out what it was. Petty has one of the other Superbirds on display in his namesake museum nearby.

After tapping the memories of the original crew members, referencing old photos and picking out a few unique features, they determined and certified that it was definitely one of the cars driven by Petty, rather than his teammate Pete Hamilton. Werner then commissioned Petty’s shop to do a full restoration that included some authentic spare parts he’d purchased from another collector.

Werner says he’s letting it go now, along with the other cars, because it’s time to move on to new things, but he also stands to make a tidy profit in the process. The car is being offered with an undisclosed reserve and Werner won’t guesstimate what he thinks it might go for.

“A car like this, there’s just no way to predict what will happen at an auction,” he said.

“If you’re older, you remember it from the racing, but to younger people it’s the Dinoco car from ‘Cars’ that was voiced by Richard Petty. Either way, everyone has a connection to it in some way.”

“It comes down to two people and how badly one of them wants it.”

He wouldn’t be surprised, though, if the hammer comes down on a bid that rivals the highest ever offered for an American racing car, like the $3.74 million Gurney Eagle, $7.25 million Shelby Daytona Cobra or even the Ford GT40 from the Steve McQueen film, “Le Mans” that sold for $11 million in 2012.