8 tracks were developed by William Powell Lear, while working at the Lear Jet Company. He is also the inventor of the Learjet. His invented the 8 track by developing a way to divide magnetic tape in 8 channels (or tracks), this increased the amount of storage space without negatively impacting sound quality. Like reel to reel, magnetic wire recording (coming soon) and later cassettes 8 tracks are a type of magnetic audio recording. They use a thin (ultimately very cheap) plastic strip with a metal oxide coating to record to.
It seems 8 tracks were pushed heavily in the automotive market. This make sense since records would be to large and delicate for automotive use (although they were used) and other media such as reel to reel would have not been feasible for many reasons. Perhaps the biggest pushed of 8 tracks was the For Motor Company by introducing them in their 1966 model year cars. According to one article I found, “…a Ford spokesperson said 65,000 players were installed in the first year”(1).
8 tracks had a short lived popularity from 1968 to 1975 and didn’t seem to take off over seas (that being said Rolle’s Royce did install them in some of their models). Their peak was in 1978 (per sales data) at a peak sales volume of $948.0 M. As they declined cassette tapes increased in popularity.
Some of the major issues with the tapes was that the quality would degrade over time, or they would simply fail and they cost more than LPs and Cassette. Based on the couple I have (unopened NOS), I can confirm this, the form tension pad has completely deteriorated.
Finally, I’ll be linking to a restoration post about this player in particular. Its old with old caps and antiquated wiring so that will need taken care of.