Earl “Madman” Muntz, an engineer and entrepreneur, created the 4-track cartridge technology (called the Stereo-Pak). This was the pivotal moment for car audio during this time period. Using advanced engineering and new-aged marketing techniques, the tape player gave car audio enthusiasts more control than ever. This new technology could play entire albums without skipping and with minimal effort from the driver. This eventually gave way to the 8-track players in the late 1960’s. By the ’70’s, when Walkman came of the scene, personalized playlists became a reality and redefined music inside and out of the automobile.