I’ve noticed there are some things that don’t make too much sense in terms of entertainment options available from the 1960s to the 1980s.
The first is the 8-track players. Currently the luxury version unlocks in 1970 and luxury cassette only appears by 1982.
In the real world, 8-track was dead by the 80s, having been replaced by cassette in the 70s. The first in-car 8-track players appeared in Fords in 1965, and they were rather common equipment by the late 60s. What I’m proposing here is luxury 8-track unlocking in 1965-66 and working its way down from there instead of the current 1970 unlock date. Also with 8-track players is that the format was so short lived that they never became the basic system for cars, so having it end at “standard 8-track” would also make sense for the format.
As far the cassette player goes, I can’t find an exact year of it being used in cars except that it was in the late 1970s, so the luxury one could make sense to unlock in 1978, perhaps? And like the 8-track, working its way down from there.
The other concern I have is for FM radio. Having FM radio could be a decent stepping stone between AM radio and 8-track, and possibly also go along with the latter as the basic option. an AM/FM radio was first used in cars in 1952, but again, I don’t know how widespread or nich that might have been. Having luxury FM in the early 1960s to mostly replace the AM-only system would make sense, as well as being the option to choose for some basic radios into the 70s instead of a basic 8-track.
Now, not sure how easy or hard it is to implement, but the AM/FM radio has been used as a basic option in cars up until recently as something much cheaper than a system with cassette or CD. So if FM radio gets implemented and it’s possible to lock it in, having it available as a basic option until at least sometime in the 00s would help to have a very low cost option for entry level cars that isn’t just “none”.