My newest car is a 2002 which has a standard size modular stereo head unit that can still be upgraded with aftermarket gear. I've been driving 2014-2016 used cars and none of them have that kind of a stereo anymore. Some have sophisticated touchscreen-driven systems for audio, climate control and navigation all in one. It doesn't seem possible to do the kind of custom car audio work that some of us grew up doing. I put a head unit plus EQ/amp into the dash of my first car (a '78 Corolla Liftback). It's not that the factory systems are so bad, but what happens when it breaks? The days of DIY car stereo repairs seem to be gone.