To re-iterate and re-enforce what 9Dave said you can create a "follow the road" route in City Navigator and then view in Topo. But if you try to recaculate the route while in Topo, your route will be straight line from waypoint to waypoint. If you want an auto-routing Topo map, I believe the 24k versions are auto-routable. I usually do not use topo when I am following a route, because map redraws are usually slower due to the greater data involved. I only switch to Topo if I want to more thoroughly investigate an area I am in. I also turn off the off-route recalculation on the gps so that an automatic recalc does not screw up my planned route. I can manually have the gps recalc a route only if I want it to.