1935
Door unlocking services
In 1935, General Motors introduced a “six cut sidebar lock” for car doors. By 1959, Chrysler started using the same type of lock on car trunks. By 1966, pin tumbler locks replaced six cut sidebar locks for trunks and doors. But no one had a true innovation — beyond a locksmith — for owners who locked their keys in their cars until remote door unlock services, such as that provided by OnStar, were developed.