1. Cigarette lighter powered radio transmitter. You plug your device into the transmitter and it transmits an FM signal that your car radio can be tuned to. These things are never powerful enough to be any good and you get crosstalk from existing FM broadcasts. Technology improvements don't matter. FCC rules about radio transmissions limit the power these things can have and the narrow band they can use.
2. Oldschool cassette tape adapter. Same as always. Plug the cable into your device, start playing the tape. Technology hasn't changed in 20 years. Bulletproof. I have one from Radioshack from the 90s that would still work.
3. Bluetooth cassette tape adater. A newer thing. Has bluetooth so it's basically a way to turn your cassette deck into a bluetooth device. I have this for my home retro HiFi system. When I got it, it wasn't working for some reason. I had to modify it by taking it apart and mechanically changing it but that may be because of the way my tape deck at home works compared to a car stereo.
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