A vehicle information system operating method performs operations comprising determining an operational period, determining a movement period, determining a modification factor, determining a fuel economy value and determining an adjusted fuel economy value. The determining of the operational period determines the operational period during which a vehicle is running. The determining of the movement period determines the movement period during which the vehicle is in motion. The determining of the modification factor determines the modification factor based on respective durations of the operational period and the movement period. The determining of the fuel economy value determines the fuel economy value associated with the operational period. The determining of the adjusted fuel economy value determines the adjusted fuel economy value based on the fuel economy value and the modification factor.