Turn-by-turn street navigation is one thing that many GPS units do well. We were primarily interested in what would happen in the dirt. Would the screen go blank from lack of dirt data? Maybe in some places, but during our time off-road in the Mojave National Preserve, the Dashdaq knew where we were and had the routes in its database. It's important to keep in mind that neither printed maps nor GPS software is perfect. The data showed some routes still existing in the Mojave National Preserve that had been closed since the data was gathered.