High Quality Content by WIKIPEDIA articles! Car audio/video (car AV), auto radio, mobile audio, 12-volt and other terms are used to describe the sound or video system fitted in an automobile. While 12-volt audio and video systems are also used, marketed, or manufactured for marine, aviation, and buses, this article focuses on cars as the most common application. From the earliest days of radio, enthusiasts had adapted domestic equipment to use in their cars. In the 1960s, tape players using reel-to-reel equipment, Compact Cassettes, and then 8-track cartridges were introduced for in-car use. Cassette players were invented before 8-tracks, therefore put in cars before 8-tracks.