How did sprint cars get their name?                                 
While watching some tapes of the Knoxville Nationals recently, I recalled that some three decades ago  I did some research on the evolution of what is now the sprint car. The research involved how “big cars” evolved from and replaced the early bobtail cars, how they had to redefine themselves when midget racing became the craze and how they finally became sprinters.
The name “sprint car” came from the type of events they ran — “sprint,” by dictionary definition, means, “to run or race at full speed for a short distance.”
Its origin was track and field, where short-running dashes were called sprints long before the car replaced the horse.
My research project had gotten sidetracked while I was getting Racing Promotion Monthly and the Promoters Workshops under way. I dug into my dusty archives the other day, found the file and refreshed my memory.
I realized how lucky I had been to be able to pick the brains of some genuine racing pioneers, including Frank Winkley, Emory Collins and Al Sweeney, who was a virtual encyclopedia of early racing history.
The cars that raced on half-mile fairgrounds horse tracks in the years surrounding World War I were mostly “bobtails,” which gained their name because there was nothing behind the driver except, in most cases, an exposed gas tank. There were no roll bars, seat belts or even crash helmets.
They were arguably the most dangerous cars in our sport’s history. Built on shortened and narrowed car frames, they used small four-cylinder engines, mostly Fords with Frontenac heads or similar early day speed equipment.  
The quest for more speed was no different then than it is today, and — there being few rules — larger cars with big engines began to challenge the lightweight bobtails, and hoods grew longer and taller to accommodate ever-larger engines.
Soon, manufacturers like Hudson, Durant, Stutz, Maxwell and others were supporting racing teams. Against these cars, the bobtails handled well but were at a horsepower disadvantage, and the big-engined cars dominated.  
Sweeney recalled that some promoters tried running the two classes in separate events, and their advertising referred to the larger cars as “big cars”— perhaps the origin of that term. Most drivers switched to bigger cars, and the days of the bobtails were numbered. The big cars grew streamlined tails, and the term “tail jobs” was popular for a time.
In the early 1930s, the midgets were created as a smaller open-wheel car to race on shorter courses like running tracks around football fields. They became the most popular racing attraction nationwide through most of the ’30s, and that created an identity crisis for the full-sized racers.
The term “big cars” was revived to differentiate between the two classes, and I recall that the name “half-mile cars” was used as well. Some advertising for big-car events stretched things a bit, referring to them as “Indianapolis-type cars.”
The midgets burned themselves out with overexposure and fields of identical Kurtis Offys, and the big cars reemerged and became the staple of open-wheel racing.
They adopted the name descriptive of the type of events they ran: sprint cars, now frequently shortened to sprinters.