Well I can navigate or I can drive the problem is doing both at the same time, thats where the sat/nav comes in handy. 8-[
I can look at the route it thinks is going to take before I set out and choose to follow it or not if I happen to know where I am going. It comes into its own in London with one way systems and closed roads.#-o
I used it going to Ally Pally and did not have to turn round or find somewhere to pull over to study the map, when the road I had planned to use was closed due to an accident, was reported on the radio. 8)