NASCAR, or the National Association for Stock Car Auto Racing, has always been and always will be about racing stock cars. Stock cars are, as a general rule, cars that are production run vehicles that have only been modified with off-the-shelf consumer parts. These cars exist in direct contrast with race cars, like those used in Formula 1 racing, that are extremely customized vehicles designed exclusively for race track use.
The origin of stock car racing in the United States can be traced directly back to the bootleggers of the Prohibition era. The bootleggers needed fast and reliable cars that could help them outrun the authorities, but the vehicles had to look like regular street vehicles to avoid unwanted attention. As such, the bootleggers would upgrade their vehicles, fine tune the engines, and otherwise enhance their cars while still keeping them inconspicuous.
Eventually, as bootleggers began working together, it was a natural extension of their obsession with their cars and speed to begin challenging each other to races. Over time (and as Prohibition ended), the bootleggers started racing each other simply for fun and organized events evolved out of their early informal racing meetups. Long after alcohol was legal again, the culture of stock car racing remained and eventually it was even formalized on a national scale through the NASCAR organization.
Lest you think the hearts of the bootleggers died out long ago and left NASCAR soulless, consider the case of one of the more popular mid-20th century NASCAR drivers, Robert “Junior” Johnson. Throughout the 1950s and 1960s, Junior was a champion NASCAR driver and then, in the 1970s and 1980s, he was a NASCAR team owner. One of Junior’s claims to true “heart-of-NASCAR” authenticity is that he not only grew up in a family of longtime bootleggers, but that he cut his racing teeth as a young man tuning his own stock car and racing it to deliver bootleg liquor just like the Prohibition era whiskey car drivers that preceded him.