The sound system in the latest 3 series is a massive upgrade on the old one.
Casting my mind back a few years, BMW used to list a reasonably inexpensive sound system upgrade, called something like Business or Professional (although they call the Sat Nav that, so it might not be the correct terminology). Anyway, it was about half the price of the Harman kardon system. They no longer list that as an option, so I’m wondering if that’s now the standard system? It could explain why we are all noticing improved standard sound systems in BMW’s.