How did the one-millionth Chevrolet Corvette get to be No. 1,000,000? No, not just by coming after No. 999,999, smart-aleck. Go sit in the corner.

Months of planning went into figuring out which Corvette would make history, and exactly when it would be built, former Corvette model-year manager Jeff Yachnin told me last week. Yachnin spent 17 years on the Corvette team.

We were talking because I got a look at the historic car undergoing restoration at GM Design headquarters in Warren, just outside Detroit. The car was damaged — virtually totaled, to the untrained eye — when a 30-foot sinkhole swallowed it and seven other cars at the National Corvette Museum in Bowling Green, Ky., on Feb. 12, 2014.

Chevrolet saw the millionth ‘Vette coming and preparations began years in advance.

Mark Phelan: Restoring historic Corvette 1

The first step was figuring out many Corvettes had already been built, Yachnin said. That’s harder than you might think. The ‘Vette is one of the few GM models on which prototypes — early cars built while developing the new model — were built on the regular assembly line.

In addition, the plant in Bowling Green builds preproduction cars — more refined than prototypes, but still not cars that can be sold to customers. On the other hand, some preproduction cars were sellable. They needed to be part of the count to one million. The ‘Vette team had to figure out exactly how many of all those vehicles had been built since ‘Vette No. 1 in 1953.

When they knew how many Corvettes had already been built, the team could see the millionth would come up around the end of the 1992 model year, or early in ’93, Yachnin said. Chevy’s marketing and public relations teams rebelled.

The 1993 model would be the Corvette’s 40th anniversary, a number that could be used to generate publicity and marketing buzz.

“They never want to use two ideas in a single model year,” Yachnin told me. “We had to make sure it was a ’92, not a ’93.”

So the juggling began. The assembly plant, workers and suppliers all teamed up to make sure the millionth ‘Vette would be a ’92. Production schedules were set and parts were ordered months in advance.

Then reality intruded. Corvette sales slowed unexpectedly in spring 1992. It looked like the magic number would come up after the summer shutdown and roll out of the factory on a 1993.

The team watched the numbers daily and threw in a few extra cars to make sure No. 1,000,000 left the factory July 2, 1992, at the last moment before the plant shut down to change over to ’93 models.

The plant also built two stunt doubles of No. 1,000,000, Yachnin said. They were identical in every way except for their vehicle identification numbers. They were used for photos and video.

Those cars were sold, undoubtedly at a premium since they’re dead ringers for the millionth ‘Vette. Given the care Corvette owners lavish on their cars, they’re probably still in circulation, while No. 1,000,000 is undergoing a thorough restoration to have it back on display in time for the museum’s 30th anniversary this Labor Day.

Contact Mark Phelan: mmphelan@freepress.com or 313-222-6731. Follow him on Twitter @mark_phelan.