You're being downvoted, but I think the comparison is worth considering.

For the average car sound-system, I doubt the quality improvement from the cassette->CD upgrade is going to be all that appreciable. The upgrade to CD only makes sense for a decent sound-system, or if cassettes are no longer available.

This seems comparable to the FM->DAB (or DAB+) upgrade. I don't know about the usage patterns here, but I suspect radio is more often used in vehicles than at home with nice speakers, or with headphones. Perhaps it's different from CD/cassette in that regard, or perhaps not.