A method of operating a PND or navigation system having - memory storing map data consisting of one or more base map data files, optionally having one or more supplemental corrective and/or ancillary data files applied or applicable thereto, - a display - GPS signal reception and processing means by means of which a current location is determinable, such together forming a basis for navigation, route guidance, and map information display on said display, and - a vehicle-specific parameter that is locally stored or derived from associated sensors and is indicative of a characteristic of the vehicle in which the PND or navigation system is commonly situated, the method including the steps of correlating the current location with said map data to derive one or more map-specific parameters for that location and comparing said one or more map-specific parameters with said vehicle-specific parameter to determine whether, for the current location, the vehicle-specific parameter is seemingly at odds with said map-specific parameter, and if so, performing a secondary action, wherein the secondary action is selected from at least one one of - automatically, or in response to a user prompt requesting verification of the apparent conflict, creating a new, or altering, qualifying, correcting or deleting a previously existing, map data correction including at least some location information and some correction identifying information, and - flagging, adding meta-data to, or otherwise identifying at least one recorded entry in GPS trace log data, such data being commonly stored in the device during operation every few seconds or other suitable period. - memory storing map data consisting of one or more base map data files, optionally having one or more supplemental corrective and/or ancillary data files applied or applicable thereto, - a display - GPS signal reception and processing means by means of which a current location is determinable, such together forming a basis for navigation, route guidance, and map information display on said display, and - a vehicle-specific parameter that is locally stored or derived from associated sensors and is indicative of a characteristic of the vehicle in which the PND or navigation system is commonly situated, the method including the steps of correlating the current location with said map data to derive one or more map-specific parameters for that location and comparing said one or more map-specific parameters with said vehicle-specific parameter to determine whether, for the current location, the vehicle-specific parameter is seemingly at odds with said map-specific parameter, and if so, performing a secondary action, wherein the secondary action is selected from at least one one of - automatically, or in response to a user prompt requesting verification of the apparent conflict, creating a new, or altering, qualifying, correcting or deleting a previously existing, map data correction including at least some location information and some correction identifying information, and - flagging, adding meta-data to, or otherwise identifying at least one recorded entry in GPS trace log data, such data being commonly stored in the device during operation every few seconds or other suitable period. - automatically, or in response to a user prompt requesting verification of the apparent conflict, creating a new, or altering, qualifying, correcting or deleting a previously existing, map data correction including at least some location information and some correction identifying information, and - flagging, adding meta-data to, or otherwise identifying at least one recorded entry in GPS trace log data, such data being commonly stored in the device during operation every few seconds or other suitable period.