What do audiophiles do in their cars?

The 14 speaker “Lexicon” in my Hyundai Genesis is remarkable to my ears, depending on the source, of course.

Have an Infiniti with one of those run-of-the-mill Bose systems with cardboard speakers and a horrible sub. Kept the stock head unit, speakers upgraded where easily accessible (to match the amp had to find 2ohm high sensitivity speakers). Replaced spare-tire sub with better spare-tire sub. Dynamatted all the doors and floors. Maybe $1,000 and some of my time for the work? Marked improvement, but as others have said, hardly a controlled listening environment. 

I use to listen to my wife but Dekay’s wife’s complaining is more interesting-as always, stuck in LA traffic

I use the stock system in my VW GLI and stream Qobuz or the Relisten app from my phone.

CD's in a fair system for 2008. Fosgate? Except the subwoofer under the driver seat. Useless except for gluteus massage. I turn the bass control down to zero. Sometimes I run a Patch cord direct to my V40 phone for Tidal. It has an above average Dac.