Forgotten audio formats: The Highway Hi-Fi

Unlike car radios—which had already been around for more than a decade—the Highway Hi-Fi actually gave you a choice. The records you wanted to play were picked by you rather than by a DJ in a radio station miles away, and those discs could hold some 90 minutes of music. This playing time was twice what you could get from a normal vinyl record of the mid-1950s—a trick accomplished by dragging the Highway Hi-Fi’s playing speed down to a mere 16.66 RPM, half that of a normal vinyl album. In technological terms, this was seen as a minor miracle. – Phil Olga, Ars Technica