I travel a lot and, in the course of that, rent cars. My habit is to take along whatever project I'm mixing or mastering, and listen to it in the rental car. I always leave the "tone" controls however the previous customer or company employee set them. (I figure this gives me a glimpse of the real world.)

I'm finding that some car players put a quick fade at the beginning of at least some tracks. For example, if the song begins with an accent (a quick transient), the car player smooths it out so it loses its BAM! If I hear that, I hit the button that sends playback to the beginning of the song, and the BAM! is intact.
If, during the middle of a song, there's a rest followed by a BAM!, the BAM! is intact.

So I'm guessing that the player is not looking ahead for transients, but simply puts a fade-in at the beginning of each track.

Is this how modern car CD players work? If so, I hate it. And I'm going to hate putting more dead air at the beginning of each track.