I am considering buying an automotive type GPS. I am leaning toward the Nuvi 750 at this point. It is my understanding that you can not load TOPO maps on most if not all ASutomotive type units. So, what does the unit show when you take the road less traveled into the mountains? I don't get into anything hard-core, but do enjoy driving around on maintained forest roads and trails. Do they show up, if they are on Google Maps for instance?