Many people use phones as Sat Nav, it's actively encouraged in some of the newer budget models with cradles etc so simply saying phones shouldn't be used in cars isn't realistic. I don't think it's a helpful addition really, just nannying.
It doesn’t interfere with the navigation or audio (music/podcasts) at all. They’ll continue to operate as normal; it just stops calls and messages from distracting you until you get to your destination.