刚买个GarminGPS，总是指向我不想走的高速，是否可以设定我想走的高速？比如我想去Fairview mall，想走86号公路，GPS总指引我走7号

or you can try use settings 15mpg city and 40mpg highway. Route Preference set for Less Fuel as a replacement for Faster Time. Avoidances set to Disabled

请问如何做 customer route？能否详细一些说？我的GPS型号是 3950。fairview mall只是个例子，我想自己设路线走一段没走过的高速。