@ Rich Powers said..."But is AM sensitivity and selectivity really much better in today's cars? I can understand how it probably was once upon a time, but now? Obviously auto manufactures don't care anymore"
Yes I agree with Rich on this one. The elimination of fender antennas for these stupid shark fins on the back of the roof and in the past the radio was the only entertainment in a car where now there's other things like streaming, pod casts and a disinterest in radio in general. Yes I think if you took a car from the 70s, just to pick a time period with a standard radio that the car came with and put a side by side test with a car new now the older car would win as Rich pointed out there's no demand for good radios now. GM Delco radios were among the best in reception and moving to the eighties when FM came in cars standard the FM then compared to now I would agree that they were better.
You also used to be able to 'delete' the car radio from your new car, and put in one of your own (or just replace it if it was already there). Aftermarket radios were superb, particularly Alpine and Kenwood. I owned a Kenwood that had a sensitivity of 0.5uv with 20db noise reduction. That, combined with the steel whip antenna, let me listen to Artisan Radio for well over 1/2 km.
Now, the radio is bundled into the electronic brains of the dashboard, and it's difficult, if not impossible, to put in something aftermarket. You'd pretty much have to install it in addition to the other one, if you had the space.