The automobile industry's shift from 8-track players to cassette decks took place in the late 1970s. Major American automakers like General Motors began offering cassette decks as an option by the 1980 model year. The 8-track format struggled through the early '80s, with cassettes capturing 51% of the market by 1984. As cassette popularity grew, 8-track reliability declined due to cost-cutting measures.
The 1966 Ford Mustang was the first car with a factory-installed 8-track player, revolutionizing in-car music by allowing drivers to choose songs beyond the radio. The technology used a continuous loop of magnetic tape divided into four programs, but its major flaw was interrupting songs every ~10 minutes to switch tracks.
Interestingly, cassette technology existed earlier, with a car player available by 1968. Initially, cassettes had inferior music quality compared to 8-tracks and were primarily used for dictation. Improvements in tape materials and noise reduction, along with the ability to play longer without interruptions, eventually led to cassettes dominating the market.