The original Highway Hi-Fi players were produced from 1957-59, and played the special 16RPM LP recordings only available through the car dealer.
The extremely fine grooves required on a 16RPM LP record made the players a constant headache, and they often skipped and distorted on anything but the most pristine pavement. An "improved" version was introduced in 1960 which played the familiar 7" 45RPM singles, but the requirement to flip records after each song limited the appeal, and it was canceled after 1961.
Lots of info on these things here:
http://www.roadkillontheweb.com/arp.html
