Seat belt design had to change in order to be acceptable to motorists and safety experts. A lap belt alone did not secure the upper body. Several full-body seat belt designs were patented in the 1950s, and one emerged as the simplest yet most effective design. In 1958, Nils Bohlin, Volvos chief safety engineer, introduced a three-point seat belt that provided lap and shoulder restraints with one smooth motion of the arm. It held the upper and lower body while placing pressure on the chest and hips; a lap belt placed pressure on the abdomen, where internal injuries could occur. The Bohlin seat belt became standard equipment on selected 1959 Volvo models and soon was applied to other Volvo models.
The National Highway Traffic Safety Administration chose air bag technology as the centerpiece of passive restraints -- safety devices that save the lives of motorists without their voluntary participation. John W. Hetrick patented an air bag operated by compressed air in 1953, and Ford, General Motors, and Eaton, Yale and Towne developed faster gas-fired air bags in the 1960s. But the road from idea to implementation was strewn with technical glitches, motorist indifference, manufacturer skepticism, and changing government policies. Mandatory air bag standards were approved and rescinded several times in the 1970s and 1980s. Meanwhile, General Motors and Ford voluntarily introduced optional air bags in 1974 and 1986 respectively.
In 1988, Chrysler became the first American auto manufacturer to install standard driver-side air bags. By 1998, federal law required dual front air bags in all new cars. A series of fatalities caused by air bags made motorists anxious, but by the early 21st century motorists were comfortable with the protection that air bags provided.