I use the car's nav only when I don't have to worry about delays caused by traffic, otherwise google maps is my first option.
BMW's nav is pretty bad in offering alternative routes based on traffic data, but I just LOVE the directions on the HUD.
I'm in the UK and my maps get updated frequently (it often has a % downloading bar for the update) and when I compare with my phone the route and traffic is very similar to Google Maps.
I use the car's nav only when I don't have to worry about delays caused by traffic, otherwise google maps is my first option.
BMW's nav is pretty bad in offering alternative routes based on traffic data, but I just LOVE the directions on the HUD.