@wkempf: The navigation algorithm is not part of the data; even Google uses the same Navteq data for most of the world, but this doesn't mean its directions will match those of Bing or Nokia Maps. And for some reason, Nokia Drive has pulled quite a few stupid stunts on me (like trying to find "clever" shortcuts that cut through a carrot patch or something).

My guess is that their algorithm uses a different balance between fastest vs shortest (and probably simplest), and that doesn't necessarily work best everywhere. Unfortunately it doesn't offer options to change that.