Method and apparatus (2) of a vehicle for alerting a driver of a vehicle when the vehicle deviates from a predefined driving area in a lane. The apparatus includes an image display unit (6) and a control unit (5) connected to each other to enable the apparatus to provide a visual warning via the image display unit when the vehicle is outside the predefined driving area and where the visual warning is displayed in the form of a solid or broken line on the side of the image display unit (6) that corresponds to the side of the vehicle where the deviation occurs.