[palimpsests]

modern mastering does not optimize fidelity in a car at the expense of other modes of listening, and these articles do not indicate as such.

modern mastering does take into account a highly popular listening environment, to ensure that the mix sounds good there as well.

the second article you posted is talking about using a car as one of several environments in which to test a mix. because it’s a “known” reference in a real-world environment (your ears are used to listening to mastered music on a car stereo).