What do audiophiles do in their cars?

The quality of the stereo system never impacts my car buying decision because nothing that is OEM (including upgrade options like Mark Levinson, B&O, etc.) is worth the price you pay. Even the renowned Lexus Mark Levinson upgrade is very poor sound quality. The speakers seem like they're made of cardboard. So I buy whatever car I like and then custom build my audio system. I do it because I drive longer distances and the music helps me relax. If your ear is "trained" to hear/notice differences in home audio setups you will also hear them in your car. I usually drive with the windows up to minimize outside interference. If I feel like a nice breeze of course the sound quality suffers but the option is mine. If you don't know whether it's worth it just go to a custom sound shop and listen to one of their demo cars while driving. 

In my collector cars I don't have music, I enjoy the car.
In my everyday cars I listen to BBC Radio 4, the best radio channel in the world, and CDs on long overseas trips where R4 is difficult to pick up; I also talk to the wife.

Sooliwen Congratulations on your first post, and welcome. You are absolutely correct about overpriced car upgrades.  This is where the manufacturers make all their profit.  If you buy used, even after just a year or two there is no premium for the fully loaded versions - if that's what you want, that's the way to buy it.

There are still some enthusiasts who compile home brewed lashups with huge amps and speakers in the boot (trunk).  This was very popular in the UK in the 70s and 80s.

GMC 2018 Sierra Z71. Factory (stock) BOSE system with a little tweaking. CD/Sat Radio/Terrestrial Radio with every drive.
Play It LOUD!

Leer at women much too young and good looking for them while remaining passively dissatisfied with the disappointing melange of muddy frequencies served up daily by their car audio system.

I have a tragically mediocre UConnect/Beats Premium stereo in my Jeep. The only thing I could say for it is, occasionally, I forget how disappointing it is on a good song at high volume.

We had an ’18 Nissan Pathfinder a couple years ago with a premium Bose system in it. It never sounded particularly good if you were listening to the radio or CD. Volume wise you really couldn’t get satisfactory punch or crank on, but on a long road trip I plugged my iPod in to listen to some albums and it sounded absolutely terrific. In fact, the iPod is the best sounding input in my current Jeep as well. Better clarity, more punch. It’s all mostly lossless stuff, well as lossless as an iPod will let you have, but the point is, if I’m plugging an outboard device with a 3.5 audio cable coming out of a headphone jack and it sounds better than anything else is going on on the head unit, most likely that head unit really sucks, which would come as no surprise to any of the posters here.