Agent,
If you are like me and pretty visual, you may try the "mouse buttons for spoken instructions" feature of S&T Keys. I am using it myself to avoid looking at my big laptop screen (turning the head) very often on long travel (highway and so on). This allows to drive mostly with voice feedback as requested (using a single ear earphone if needed), controlled with a touch of a mouse button (that you put near you in a strategic location so you don't need to look at it to use it). The purpose is to keep the eye on the road most of the time which is still difficult for me (i am often trying to look at the screen. So voice guidance can allow to close the screen when not in critical city driving)... With this feature, you may ask anytime S&T to give you how many km are there till the next turn without using/touching/looking at your laptop at all...
See instructions of S&T Keys 2009 (link in my signature) about it and also the link on an experiment i have done with it...
Good travelling