On a recent trip we got a car with GPS, even without asking. On the 3rd or 4th time through the same neighborhood I realized that I still didn't know how to get through it without the navigational unit. The GPS was such a crutch that I wasn't cognizing the spatial patterns, even with repetition.
Presumably this is connected somehow to the recent findings of Toru Ishikawa, Hiromichi Fujiwara, Osamu Imai, and Atsuyuki Okabe in the Journal of Environmental Behavior. They studied the effect of GPS on walking and found that GPS slowed people down but that they ended up walking farther and stopping more than people with maps or people exploring.