As far as I know, all the automotive GPS units Garmin is releasing also have the turn by turn with street names. I know they were working toward that when I left the company 9 months ago.
Which Verizon phone do you have? I have the LV enV but I have only tried the navigation with the phone open. The voice guidance on mine is very quiet and I haven't found a way to get the volume to go higher than it already is. I also haven't tried it with the phone closed, so I may do that too.