once the Mount has secured a GPS lock (takes a couple mins from a cold start) all apps using Location Services will use the mount ... i've tested by looking at the MotionX GPS app which gives an "accuracy" value ... the mount provides an incrementally better fix accuracy, and after a couple mins from cold start, the app jumps to that fix accuracy indicating that all apps, incl. TomTom, will use the improved fix. Hope that helps.