Many of the popular G.P.S. systems such as Magellan,Tom-Tom and Garmin are preset to use the shortest
route/quickest time to guide you to your destination. To avoid dirt roads and single track roads, you should use the "most use of highways/avoid dirt road"
feature. Using "quickest route" can place you on narrow back roads that are not well marked and may not be fit to drive on with your 4X4, let alone your passenger car or motor home.