I can use that feature with My Mio GPS unit, too. Unfortunately, the areas I bike in most frequently during good weather are the unimproved forest roads in the national forest that I live in and they aren't on any commercial maps and most aren't even mapped by Google. Fortunately, I can run Ozi Explorer CE on my Mio since I've hacked it to run Mio Pocket. That allows me to import the USGS free topo maps of the forest. These are about the only maps that have most of the unimproved forest roads mapped out.