The aftermarket filled the hole quickly and with the full range of quality available. Many people put the early "discman" portable players on the dash and used FM modulators to get that signal to the car radio.
When "factory CD" units started to appear they were multiples of the price of aftermarket units, and initially of such low quality initially that the FM modulators sounded better. The disc handling on some of the early units was ludicrous, too: "just get my CD out please" was common.
* edit: also people used "CD to cassette adapters" which are worth mentioning because of how ingenious they are. Its a headphone plug on one end and a cassette shell on the other, the headphones drive coils that excite the tape player's read head.
Source: installed car audio as a sideline in the late 80s early 90s.
When "factory CD" units started to appear they were multiples of the price of aftermarket units, and initially of such low quality initially that the FM modulators sounded better. The disc handling on some of the early units was ludicrous, too: "just get my CD out please" was common.
* edit: also people used "CD to cassette adapters" which are worth mentioning because of how ingenious they are. Its a headphone plug on one end and a cassette shell on the other, the headphones drive coils that excite the tape player's read head.
Source: installed car audio as a sideline in the late 80s early 90s.