Ford celebrated the production of the 10 millionth Mustang last week, but the story behind the first Mustang sold is far more interesting.

Speaking with the Detroit Free Press, Tom and Gail Wise revealed the bizarre story of their Mustang and the fact they didn’t realize they owned the first Mustang ever sold.

After purchasing the car in 1964, Gail and her family drove the model for 15 years before it stopped working. The car spent the next 27 years in the couple’s garage and they eventually debated whether they should continue holding onto it or sell it for scrap. Tom convinced his wife that they should keep the car because he would eventually find the time to fix it up. This sparked a series of events which would eventually reveal the Mustang’s origins.

Once Tom retired, he started looking for replacement parts for the car and found someone claiming to be the first Mustang owner. That person said they bought their car on April 16th 1964, but Tom thought Gail had purchased her Mustang one day earlier.

The couple eventually dug through their records and discovered the original receipt which confirmed she bought the Mustang on April 15th. This was two days before the car was officially unveiled at the World’s Fair in New York.

How she managed to get a hold of the car before the unveiling was a combination of luck and an eager salesperson. As Gale explained to the paper, she went to her local Ford dealership in Chicago and told the salesperson she wanted a convertible. The dealership didn’t have any on the lot, but they received two Mustangs – a coupe and a convertible – to show potential customers after the car made its debut on April 17th. While the dealer was supposed to hold onto the cars, the salesperson sold the convertible to Gail who drove it home that same day.

The car only has 68,000 miles (109,435 km) on it and has now been fully restored. It’s a good thing the family decided to hold onto to as model as it is believed to be worth between $350,000 (£275,345 / €308,577) and $450,000 (£354,015 / €396,742).  That’s significantly more than the original purchase price of $3,447.50 (£2,712.15 / €3,039.33).