A process for guiding a vehicle along a route to a predetermined destination point includes determining a route in the form of consecutive path points which include at least geographic coordinates, determining the linear distance between a current location and the next path point and/or determining a change in the direction of travel between path points or at a path point. The process also provides a departure from route warning if (1) the linear distance is the next path point is more than a predetermined value; (2) a change in direction between path points lies outside of an allowed range or (3) a change in direction at a path point deviates from a target change in direction by more than a predetermined tolerance value.