..GPSS (the one i used) does exactly what you are trying to achive, plus some more. the problem with it is that extra features", i mean in a carputer setup with a small screen, you will only need the very basic information such as the moving map, speed, long/lat, and some few, the rest of your attention should be on the road. plus GPSS talk too much, and interface is the worst i have ever seen (sor