Neyhart joined the faculty of Pennsylvania State University in 1929 as an assistant professor of industrial engineering. (He earned his bachelor's and master's degrees at the same institution.) Around 1931, when a drunk driver hit Neyhart's parked car, he became convinced of the need for teenagers to be educated in how to drive properly. Parents lacked the necessary objectivity and patience to teach their children to drive, he believed, and they also often unknowingly passed along their own bad driving habits. Neyhart began by teaching volunteer students from State College High School; he used his own 1929 Graham-Paige automobile, which he had specially fitted with dual brake and clutch linkages. In 1933, he established a formal course at the high school, and he soon developed a teacher-preparation program. In 1934, Neyhart published "The Safe Operation of an Automobile," the first textbook on driver education.
Neyhart's pioneering work in Pennsylvania soon caught on across the country. By 1968, according to an article that year in The New York Times, accredited driver education courses were offered in more than 71 percent of the nation's high schools. A study completed at the time by the New York State Department of Motor Vehicles found that graduates of such courses were involved in 22 percent fewer accidents and had 50 percent fewer driving violations than non-graduates, and most insurance companies had begun granting discounts to accredited young drivers.
Beginning in the late 1930s, Neyhart served as a consultant on driver education for the American Automobile Association (AAA); he was also director of Penn State's Institute of Public Safety in Continuing Education. Presidents Harry S. Truman, John F. Kennedy and Lyndon B. Johnson all named him to national traffic safety committees during their administrations. In 1988, Neyhart was inducted into the Safety and Health Hall of Fame International.