According to a new research study from NAVTEQ, drivers can save as much as $200 a year by using GPS systems. The study found that when drivers used navigation systems to get around they consumed 12% less fuel than those that drove without it. Over a year's time, the average driver could drive 1500 fewer miles using the device. Navigation users who use devices like OnStar's voice activated Turn-by Turn system also report less stress while driving. In addition, this Black Friday, the biggest shopping day of the year, OnStar is letting all of their Turn-by Turn enabled subscribers use the service for free.