As NASCAR's popularity boomed in the 1950s, auto manufacturers began to get more involved in the sport by giving "factory backing" to individual drivers. Simply put, they paid drivers to drive their cars. There was a popular motto that caught on with the manufacturers during this time: "win on Sunday, sell on Monday" [source: AeroWarriors].
However, in 1957 all the automobile manufacturers pulled out of racing after an 8-year-old boy and five others were injured by the flying debris from an accident.
It would be five years before the manufacturers returned to NASCAR and seven years before Chrysler introduced the 426-cubic-inch (6,980 cubic cm) hemispherical engine, more commonly referred to as the "hemi." The powerful new engine immediately began to dominate the sport, and competition suffered. After a single season of racing, Bill France outlawed the hemi and Chrysler pulled out of NASCAR in protest. In 1966 France allowed a modified version of the hemi, and Chrysler immediately returned [source: NASCARonlinebetting].
By the late 1960s most of the auto manufacturers were producing the most powerful engines they could produce and still legally race. Smaller and smaller horsepower gains were becoming increasingly expensive to obtain. So the manufacturers turned their attention to a new frontier -- aerodynamics.
It was the beginning of the "aero wars," a great competition between auto manufacturers to produce the most aerodynamic car in the sport. The main competitors were Chrysler and Ford, who both claimed to have come out on top when the dust settled [source: AeroWarriors]. Eventually, France stepped in to introduce an engine-size limit, and many drivers switched back to the classic stock builds.
With drivers reaching speeds of more than 200 mph (322 km per hour), safety has become a much larger focus. Certain speedways now require restrictor plates, which slow cars down. The message is clear: Until the cars are safer, they can't go any faster. Auto manufacturers will no doubt play a large role in the continued development of safer, faster stock cars.